Codeforces : From Newbie to Expert (900-Rated)

so ... I will be sharing all solutions here (recent solutions at the top, or find by ctrl+f)

                                

900 Rated Problems Link : ProblemSet

Video Explanations : Check Here

75. Alarm Clock

1. #include<bits/stdc++.h>
2. using namespace std;
3. #define ll long long
4.  
5. int main(){
6. int t; cin>>t;
7. while(t--){
8. ll a, b, c, d; cin>>a>>b>>c>>d;
9. ll sleep = -1;
10. if(b>=a) sleep = b;
11. else {
12. if(d>=c) sleep=-1;
13. else sleep = b + c*((a-b+c-d-1)/(c-d));
14. }
15. cout<<sleep<<endl;
16. }
17. }

74. Chips Moving

1. #include<bits/stdc++.h>
2. using namespace std;
3. int main(){
4. int n; cin>>n;
5. int odd=0;
6. for(int i=0; i<n; i++){
7. int x; cin>>x;
8. odd += x & 1;
9. }
10. cout<<min(odd, n-odd)<<endl;
11. }

73. Maximums

1. #include<bits/stdc++.h>
2. using namespace std;
3. int main(){
4. int n; cin>>n;
5. int x=0;
6. for(int i=0; i<n; i++){
7. int b; cin>>b;
8. int a = b + x;
9. x = max(x,a);
10. cout<<a<<' ';
11. }
12. cout<<endl;
14. }

72. Chemistry

1. #include<bits/stdc++.h>
2. using namespace std;
3. int main(){
4. int t; cin>>t;
5. while(t--){
6. int n, k; cin>>n>>k;
7. string s; cin>>s;
8. map<char,int> m;
10. for(int i=0; i<n; i++) m[s[i]]++;
11.  
12. int count=0;
13. for(int i='a'; i<='z'; i++)
14. if(m[i]%2) count++;
16. if(count>k+1) cout<<"NO"<<endl;
17. else cout<<"YES"<<endl;
18. }
19. }

71. Following the String

1. #include<bits/stdc++.h>
2. using namespace std;
3. int main(){
4. int t; cin>>t;
5. while(t--){
6. int n; cin>>n;
7. map<char, int> freq;
8. string s = "";
10. for(int i=0; i<n; i++){
11. int a; cin>>a;
12. for(char c='a'; c<='z'; c++)
13. if(freq[c]==a){
14. s.push_back(c);
15. freq[c]++;
16. break;
17. }
18. }
19. cout<<s<<endl;
20. }
21.  
22. }

70. Make It Increasing

1. #include<bits/stdc++.h>
2. using namespace std;
3. int main(){
4. int t; cin>>t;
5. while(t--){
6. int n; cin>>n;
7. vector<int> a(n);
8. for(auto &i: a) cin>>i;
9. int ans=0, flag=1;
10. for(int i=n-2; i>=0; i--){
11. while(a[i]>=a[i+1] && a[i]>0){
12. a[i]/=2;
13. ans++;
14. }
15. if(a[i]==a[i+1])
16. {cout<<-1<<endl; flag=0; break;}
17. }
18. if(flag) cout<<ans<<endl;
19. }
20. }

69. Long Comparison

1. #include<bits/stdc++.h>
2. using namespace std;
3.  
4. int main(){
5. int t; cin>>t;
6. while(t--){
7. double a, b, c, d;
8. cin>>a>>b>>c>>d;
9. double x = log10(a) + b, y = log10(c) + d;
10. if(abs(x - y) <= 1e-7) cout<<"="<<endl;
11. else if(x>y) cout<<">"<<endl;
12. else cout<<"<"<<endl;
13. }
14. }

68. Odd Grasshopper

1. #include<bits/stdc++.h>
2. using namespace std;
3. typedef long long ll;
5. int main(){
6. int t; cin>>t;
7. while(t--){
8. ll x, n; cin>>x>>n;
9. ll ans = x;
10. if(x%2==0){
11. if(n%4==1) ans-=n;
12. else if(n%4==2) ans++;
13. else if(n%4==3) ans += n+1;
14. }
15. else{
16. if(n%4==1) ans+=n;
17. else if(n%4==2) ans--;
18. else if(n%4==3) ans -= n+1;
19. }
20. cout<<ans<<endl;
21. }
22. }

67. Strange Partition

1. #include<bits/stdc++.h>
2. using namespace std;
3. int main(){
4. int t; cin>>t;
5. while(t--){
6. long long int n, x, y, _max=0, _min=0;
7. cin>>n>>x;
8. for(int i=0; i<n; i++){
9. cin>>y;
10. _min += y;
11. _max += (y + x - 1)/x;
12. }
13. cout<<(_min + x - 1)/x<<" "<<_max<<endl;
14. }
15. }

66. Wizard of Orz

1. #include<bits/stdc++.h>
2. using namespace std;
3. int main(){
4. int t; cin>>t;
5. while(t--){
6. int n; cin>>n;
7. string s = "989";
8. if(n==1) cout<<"9"<<endl;
9. if(n==2) cout<<"98"<<endl;
10. if(n>=3){
11. cout<<s;
12. for(int i=0; i<n-3; i++)
13. cout<<i%10;
14. cout<<endl;
15. }
16. }
17. }

65. Tricky Sum

1. #include<bits/stdc++.h>
2. using namespace std;
3. int main(){
4. int t; cin>>t;
5. while(t--){
6. long long int n, s, pow2=1;
7. cin>>n;
8. s = n*(n+1)/2;
9. while(pow2<=n)
10. s -= pow2*2, pow2 *= 2;
11. cout<<s<<endl;
12. }
13. }

64. Permutation Sort

1. #include<bits/stdc++.h>
2. using namespace std;
3.  
4. int main(){
5. int t;
6. cin >> t;
7.  
8. while(t--){
9. int n;
10. cin >> n;
11.  
12. vector<int> a(n);
13. for(int &i : a)
14. cin >> i;
15.  
16. int ans = 2;
17.  
18. if (is_sorted(a.begin(), a.end()))
19. ans = 0;
20. else if (a[0] == 1 || a[n - 1] == n)
21. ans = 1;
22. else if (a[0] == n && a[n - 1] == 1)
23. ans = 3;
24.  
25. cout << ans << endl;
26. }
27. return 0;
28. }

63. Make it Divisible by 25

1. #include<bits/stdc++.h>
2. using namespace std;
3. int main(){
4. int t; cin>>t;
5. while(t--){
6. string s; cin>>s;
7. int n = s.size();
8. int ans=INT_MAX;
9. for(int i=0; i<n; i++){
10. for(int j=i+1; j<n; j++){
11. int no = s[i]-'0';
12. no = no*10 + s[j]-'0';
13. if(no%25==0)
14. ans = min(ans, j-i-1+n-j-1);
15. }
16. }
17. cout<<ans<<endl;
18. }
19. }

62. Hexadecimal's theorem

1. #include<bits/stdc++.h>
2. using namespace std;
3. int main(){
4. int n; cin>>n;
5. cout<<n<<" "<<0<<" "<<0<<endl;
6. }

61. Sending Messages

1. #include<bits/stdc++.h>
2. using namespace std;
3. int main(){
4. int t; cin>>t;
5. while(t--){
6. long long int n, f, a, b, temp=0;
7. cin>>n>>f>>a>>b;
8. for(int i=0; i<n; i++){
9. long long int val;
10. cin>>val;
11. f -= min((val-temp)*a,b); //per second cost = a
12. temp = val; //restart cost = b
13. }
14. cout<<(f>0?"YES":"NO")<<endl;
15. }
16. }

60. Unnatural Language Processing

1. #include<bits/stdc++.h>
2. using namespace std;
3. int main(){
4. int t,n;
5. cin>>t;
6. while(t--){
7. string s; cin>>n>>s;
8. cout<<s[0];
9. for(int i=1; i<n; i++){
10. if((s[i+1]=='a'|| s[i+1]=='e'))
11. cout<<".";
12. cout<<s[i];
13. }
14. cout<<endl;
15. }
16. }

59. Devu, the Singer and Churu, the Joker

1. #include<bits/stdc++.h>
2. using namespace std;
3. int main(){
4. int n, d, sum = 0;
5. cin>>n>>d;
6. int a[n];
7. for(int i=0; i<n; i++) cin>>a[i], sum+=a[i];
8. if(sum + (n-1)*10 > d) cout<<-1<<endl;
9. else cout<< (d-sum)/5<<endl;
10. }

58. Shifting Stacks

1. #include<bits/stdc++.h>
2. using namespace std;
3. int main(){
4. int t; cin>>t;
5. while(t--){
6. int n; cin>>n;
7. vector<int> a(n);
8. for(auto &i:a) cin>>i;
9. long long sum = 0, req = 0, flag=0;
10. for(int i=0; i<n; i++){
11. req += i;
12. sum += a[i];
13. if(sum<req) flag=1;
14. }
15. cout<<(flag==0?"YES\n":"NO\n");
16. }
17. }

57. Comparison String

1. #include<bits/stdc++.h>
2. using namespace std;
3.  
4. int main(){
5. int t; cin>>t;
6. while(t--){
7. int n; cin>>n;
8. string s; cin>>s;
9. int ans = 1, cnt = 1;
10.  
11. for(int i=1; i<n; i++){
12. if(s[i]!=s[i-1]) cnt=1;
13. else cnt++;
14. ans = max(ans, cnt);
15. }
16. cout<<ans+1<<endl;
17. }
18. }

56. Restore the Weather

1. #include<bits/stdc++.h>
2. using namespace std;
3. int main(){
4. int t; cin>>t;
6. while(t--){
7. int n,k; cin>>n>>k;
8. int ans[n], b[n];
9. pair<int, int> a[n];
11. for(int i=1; i<=n; i++){
12. cin>>a[i].first;
13. a[i].second = i;
14. }
16. for(int i=1; i<=n; i++)
17. cin>>b[i];
19. sort(a+1, a+n+1);
20. sort(b+1, b+n+1);
22. for(int i=1; i<=n; i++)
23. ans[a[i].second] = b[i];
25. for(int i=1; i<=n;i++)
26. cout<<ans[i]<<" ";
27. cout<<endl;
28. }
29. }

55. Promo

1. #include<bits/stdc++.h>
2. using namespace std;
3. int main(){
4. int n,q; cin>>n>>q;
5. long long int a[n],b[n];
6. for(int i=1; i<=n; i++) cin>>a[i];
7. sort(a+1,a+n+1,greater<int>());
8.  
9. for(int i=1; i<=n; i++)
10. b[i]=b[i-1] + a[i];
11.  
12. while(q--){
13. int x, y; cin>>x>>y;
14. y = x-y;
15. cout<<b[x]-b[y]<<endl;
16. }
17. }

54. Yet Another Tetris Problem

1. #include<bits/stdc++.h>
2. using namespace std;
3. int main(){
4. int t; cin>>t;
5. while(t--){
6. int n; cin>>n;
7. vector<int> a(n);
8. for(int i=0; i<n; i++) cin>>a[i];
9. bool possible=true;
10. for(int i=0; i<n; i++)
11. if(a[i]%2!=a[0]%2)
12. possible=false;
13. cout<<(possible?"YES":"NO")<<endl;
14. }
16. }

53. Vasilije in Cacak

1. #include<bits/stdc++.h>
2. #define ll long long
3. using namespace std;
4.  
5. int main(){
6. int t; cin>>t;
7. while(t--){
8. ll n, k, x;
9. cin>>n>>k>>x;
10. ll total = n*(n+1)/2;
11. ll min_sum = k*(k+1)/2;
12. ll max_sum = total - (n-k)*(n-k+1)/2;
13. if(x>= min_sum and x<=max_sum)
14. cout<<"YES"<<endl;
15. else cout<<"NO"<<endl;
16. }
17. }

52. Decoding

1. #include<bits/stdc++.h>
2. using namespace std;
3.  
4. int main() {
5. int n; cin >> n;
6. string s; cin >> s;
7.  
8. if (n & 1) {
9. for (int i = n - 1; i >= 0; i--) {
10. if (i % 2 == 1) cout << s[i];
11. }
12. for (int i = 0; i < n; i++) {
13. if (i % 2 == 0) cout << s[i];
14. }
15. } else {
16. for (int i = n - 1; i >= 0; i--) {
17. if (i % 2 == 0) cout << s[i];
18. }
19. for (int i = 0; i < n; i++) {
20. if (i % 2 == 1) cout << s[i];
21. }
22. }
23.  
24. return 0;
25. }

51. Oath of the Night's Watch

1. #include<bits/stdc++.h>
2. using namespace std;
3. int main(){
4. int n; cin>>n;
5. int a[n], mx=INT_MIN, mn=INT_MAX;
6. for(int i=0; i<n; i++){
7. cin>>a[i];
8. mx = max(mx,a[i]);
9. mn = min(mn, a[i]);
10. }
12. int cnt_max=0, cnt_min=0;
13.  
14. for(int i=0; i<n; i++) {
15. if(a[i]==mx) cnt_max++;
16. if(a[i]==mn) cnt_min++;
17. }
18.  
19. if(mx==mn) cout<<0;
20. else cout<<(n - cnt_max - cnt_min);
21. return 0;
22. }

50. Exciting Bets

1. #include<bits/stdc++.h>
2. using namespace std;
3. #define ll long long
4. int main(){
5. int t; cin>>t;
6. while(t--){
7. ll a,b;
8. cin>>a>>b;
9. if(a==b) cout<<0<<" "<<0<<'\n';
10. else{
11. ll x = abs(a-b);
12. ll y = a%x;
13. y = min(y, x-y);
14. cout<<x<<" "<<y<<'\n';
15. }
16. }
17. }

49. Orac and Factors

1. #include<bits/stdc++.h>
2. using namespace std;
3. int main(){
4. int t; cin>>t;
5. while(t--){
6. long long int n,k;
7. cin>>n>>k;
8. if(n%2==0) cout<<n+2*k<<endl;
9. else {
10. int d;
11. for(int i=n; i>2; i--)
12. if(n%i==0) d = i;
13. cout<<n+d+ 2*(k-1)<<endl;
14. }
15. }
16. }

48. The Corridor or There and Back Again

1. #include<bits/stdc++.h>
2. using namespace std;
3. int main(){
4. int t; cin>>t;
5. while(t--){
6. int n; cin>>n;
7. int k=INT_MAX, room, timer;
8. vector<pair<int, int>> v;
10. for(int i=0; i<n; i++){
11. cin>>room>>timer;
12. v.push_back({room, timer});
13. }
14.  
15. for(int i=0; i<v.size(); i++)
16. k = min(k, v[i].first + (v[i].second-1)/2);
17. cout<<k<<endl;
18. }
19. }

47. Make Product Equal One

1. #include<bits/stdc++.h>
2. using namespace std;
3.  
4. int main(){
5. int n; cin>>n;
6. long long int z=0, neg=0, c=0;
7. while(n--){
8. long long int a; cin>>a;
9. if(a==0) z++;
10. else if(a>0) c+= a-1;
11. else c+= -a-1, neg++;
12. }
13. if(z) c += z;
14. else if(neg%2==1) c+=2;
15. cout<<c<<endl;
16. }

46. Odd Queries

1. #include<bits/stdc++.h>
2. using namespace std;
3. long long n, q, t, a[200005], pref[200005];
4. int main(){
5. cin>>t;
6. while(t--){
7. cin>>n>>q;
10. for(int i=1;i<=n; i++){
11. cin>>a[i];
12. pref[i] = pref[i-1]+a[i];
13. }
15. for(int i=0;i<q; i++){
16. long long l,r,k; cin>>l>>r>>k;
17. long long sum = pref[l-1] + (r-l+1)*k + pref[n]-pref[r];
18. if(sum%2==1) cout<<"YES"<<endl;
19. else cout<<"NO"<<endl;
20. }
21. }
22. }

45. Dominant Piranha

1. #include<bits/stdc++.h>
2. using namespace std;
3. int main(){
4. int t; cin>>t;
5. while(t--){
6. int n, mx=0; cin>>n;
7. vector<int> a(n);
8. for(auto &p:a) {cin>>p; mx=max(mx,p);}
9.  
10. int idx=-1;
11. for(int i=0; i<n; i++){
12. if(a[i]!=mx) continue;
13. if(i>0 && a[i-1]!=mx || i<n-1 && a[i+1]!=mx) idx=i+1;
14. }
15. cout<<idx<<endl;
16. }
17. return 0;
18. }

44. Lunch Rush

1. #include<bits/stdc++.h>
2. using namespace std;
3. int main(){
4. int n, k;
5. cin>>n>>k;
6. int f, t, m = INT_MIN;
7. while(n--){
8. cin>>f>>t;
9. m = max(m, (t>k)?(f+k-t):f);
10. }
11. cout<<m;
12. }

43. DIV + MOD

1. #include<bits/stdc++.h>
2. using namespace std;
3. int main(){
4. int t; cin>>t;
5. while(t--){
6. int l,r,x;
7. cin>>l>>r>>x;
8. int ans = r/x + r%x;
9. int m = r/x*x - 1;
10. if(m>=l) ans = max(ans, m/x + m%x);
11. cout<<ans<<endl;
12. }
13. }

42. Almost Prime

1. #include<bits/stdc++.h>
2. using namespace std;
3. int a[3001];
4. int main(){
5. int n, cnt=0; cin>>n;
6. for(int i=2; i<=n; i++){
7. if(a[i]==0) {
8. for(int j=i; j<=n; j+=i) a[j]++;
9. }
10. if(a[i]==2) cnt++;
11. }
12. cout<<cnt<<endl;
13. }

41. Distance and Axis

1. #include<bits/stdc++.h>
2. using namespace std;
3.  
4. int main(){
5. int t; cin>>t;
6. while(t--){
7. int a,k; cin>>a>>k;
8. if(a<k) cout<<k-a<<endl;
9. else cout<<(a+k)%2<<endl;
10. }
11. }

40. PizzaForces

1. #include<bits/stdc++.h>
2. using namespace std;
3. int main(){
4. int t; cin>>t;
5. while(t--){
6. long long n; cin>>n;
7. cout<<max(6LL,n+1)/2*5<<endl;
8. }
9. }

39. Bad Boy

1. #include<bits/stdc++.h>
2. using namespace std;
3. int main(){
4. int t; cin>>t;
5. while(t--){
6. int n, m, i, j;
7. cin>>n>>m>>i>>j;
8. cout<<1<<" "<<1<<" "<<n<<" "<<m<<"\n";
9. }
10. }

38. Mocha and Math

1. #include<bits/stdc++.h>
2. using namespace std;
3. int main(){
4. int t; cin>>t;
5. while(t--){
6. int n; cin>>n;
7. int a[n];
8. for(int i=0; i<n; i++) cin>>a[i];
9. int j = a[0];
10. for(int i=1; i<n; i++)
11. j &= a[i];
12. cout<<j<<endl;
13. }
14. }

37. Lights Out

1. #include<bits/stdc++.h>
2. using namespace std;
3. int main(){
4. int a[5][5];
5. memset(a,0,sizeof(a));
6. for(int i=1; i<=3; i++)
7. for(int j=1; j<=3; j++)
8. cin>>a[i][j];
9. for(int i=1; i<=3; i++, cout<<endl)
10. for(int j=1; j<=3; j++)
11. cout<<(( a[i][j]
12. + a[i-1][j]
13. + a[i+1][j]
14. + a[i][j-1]
15. + a[i][j+1] ) %2==0);
16. }

36. Everyone Loves to Sleep

1. #include<bits/stdc++.h>
2. using namespace std;
3.  
4. int main(){
5. int t; cin>>t;
6. while(t--){
7. int n,h, m; cin>>n>>h>>m;
8. int t1 = 60*h+m; //cout<<t1<<endl;
9. int ans = 24*60;
10. for(int i=0; i<n; i++){
11. cin>>h>>m;
12. int t2=60*h+m-t1;
13. if(t2<0) t2+=24*60;
14. ans = min(ans, t2);
15. }
16. cout<<ans/60<<" "<<ans%60<<endl;
17. }
18. }

35. Nastya and Rice

1. #include<bits/stdc++.h>
2. using namespace std;
3.  
4. int main(){
5. int t; cin>>t;
6. while(t--){
7. int n, a, b, c, d;
8. cin>>n>>a>>b>>c>>d;
9. int l=n*(a-b), r=n*(a+b);
10. if(r<c-d || c+d<l) cout<<"No\n";
11. else cout<<"Yes\n";
12. }
13. }

34. Juicer

1. #include<bits/stdc++.h>
2. using namespace std;
3.  
4. int main(){
5. int n, b, d, a, sum=0, cnt=0;
6. cin>>n>>b>>d;
7. for(int i=0; i<n; i++){
8. cin>>a;
9. if(a<=b) sum+=a;
10. if(sum>d) sum=0, cnt++;
11. }
12. cout<<cnt;
13. }

33. Balanced Round

1. #include<bits/stdc++.h>
2. using namespace std;
3.  
4. void solve(){
5. int n, k; cin>>n>>k;
6. vector<int> a(n);
7. for(auto &i:a ) cin>>i;
8. sort(a.begin(), a.end());
9.  
10. int cnt=1, ans=1;
11. for(int i=1; i<n; i++){
12. if(a[i]-a[i-1]>k) cnt=1;
13. else cnt++;
14. ans = max(cnt, ans);
15. }
16. cout<<n-ans<<endl;
17. }
18.  
19. int main(){
20. int t; cin>>t;
21. while(t--) solve();
22. }

32. Food Buying

1. #include<bits/stdc++.h>
2. using namespace std;
3.  
4. int main(){
5. int t; cin>>t;
6. while(t--){
7. int n; cin>>n;
8. cout<<n+(n-1)/9<<endl;
9. }
10. }

31. Array Reodering

1. #include<bits/stdc++.h>
2. using namespace std;
3.  
4. int main(){
5. int t; cin>>t;
6. while(t--){
7. int n, ans=0; cin>>n;
8. vector<int> a(n);
9. for(int &x: a) cin>>x;
10.  
11. //sorting based on even/odd
12. sort(a.begin(), a.end(), [](int x, int y){return x%2 < y%2;});
13.  
14. //cnt no. of good index pairs
15. for(int i=0; i<n; i++){
16. for(int j=i+1; j<n; j++){
17. ans += __gcd(a[i],a[j]*2)>1;
18. }
19. }
21. cout<<ans<<endl;
22. }
23. }

30. Stripes

1. #include<bits/stdc++.h>
2. using namespace std;
3.  
4. int main(){
5. int t; cin>>t;
6. while(t--){
7. bool red=false;
8. for(int i=1; i<=8; i++){
9. string s; cin>>s;
10. if(s=="RRRRRRRR") red=true;
11. }
12. if(red) cout<<"R"<<endl;
13. else cout<<"B"<<endl;
14. }
15. }

29. Lineland Mail

1. #include<bits/stdc++.h>
2. using namespace std;
3.  
4. int main(){
5. int n; cin>>n;
6. int a[n];
7.  
8. for(int i=0; i<n; i++) cin>>a[i];
9.  
10. cout<<abs(a[0]-a[1])<<" "<<abs(a[0]-a[n-1])<<endl;
11.  
12. for(int i=1; i<n-1; i++)
13. cout<<min(abs(a[i]-a[i-1]),abs(a[i]-a[i+1]))<<" "<<max(abs(a[i]-a[0]),abs(a[i]-a[n-1]))<<endl;
14.  
15. cout<<abs(a[n-1]-a[n-2])<<" "<<abs(a[n-1]-a[0])<<endl;
16.  
17. return 0;
18.  
19. }

28. Unique Number

1. #include<bits/stdc++.h>
2. using namespace std;
3.  
4. int main(){
5. int t; cin>>t;
6. while(t--){
7. int n; cin>>n;
8. string s;
9. for(int i=9; i>0; i--) {
10. if(n>=i) s=to_string(i)+s, n-=i;
11. }
12. cout << (n==0 ? s : "-1") << "\n";
13. }
14. }

27. Filling Diamonds

1. #include<bits/stdc++.h>
2. using namespace std;
3.  
4. int main(){
5. int t; cin>>t;
6. while(t--){
7. int n; cin>>n; cout<<n<<endl;
8. }
9. }

26. 01 Game

1. #include<bits/stdc++.h>
2. using namespace std;
3. int main(){
4. int t; cin>>t;
5. while(t--){
6. string s; cin>>s;
7. int a[2] = {};
8. for(char c : s) a[c-'0']++;
9. cout<<(min(a[0],a[1])%2?"DA":"NET")<<endl;
10. }
11. }

25. Party

1. #include<bits/stdc++.h>
2. using namespace std;
3. int main(){
4. int n, a[2000], temp, ans=0, cnt;
5. cin>>n;
6. for(int i=1; i<=n; i++){
7. cin>>a[i];
8. }
9. for(int i=1; i<=n; i++){
10. temp = a[i], cnt=1;
11. while(temp!=-1) cnt++, temp = a[temp];
12. ans = max(ans, cnt);
13. }
14. cout<<ans;
15. }

24. Magic Numbers

1. #include<bits/stdc++.h>
2. using namespace std;
3.  
4. int main(){
5. string s; cin>>s;
6. for(int i=0; i<s.length();){
7.  
8. if(s[i]!='1' && s[i]!='4') {cout<<"NO"; return 0;}
10. else if(s[i]=='1' && s[i+1]=='4' && s[i+2]=='4') i+=3;
11. else if(s[i]=='1' && s[i+1]=='4') i+=2;
12.  
13. else if(s[i]=='1') i++;
14.  
15. else { cout<<"NO"; return 0;}
16. }
17. cout<<"YES";
18. }

23. Kana and Dragon Quest game

1. #include<bits/stdc++.h>
2. using namespace std;
3.  
4. int main(){
5. int t; cin>>t;
6. while(t--){
7. int x,n,m; cin>>x>>n>>m;
8. while(n--){
9. int temp = (x/2)+10;
10. if(x<=temp) break;
11. x = temp;
12. }
13. if(x<=m*10) cout<<"YES"<<endl;
14. else cout<<"NO"<<endl;
15. }
16. }

22. Make AP

1. #include<bits/stdc++.h>
2. using namespace std;
3.  
4. int main(){
5. int t; cin>>t;
7. while(t--){
9. int a, b, c; cin>>a>>b>>c;
10.  
11. //ye actual hai
12. int A = b - (c-b);
13. int B = a + (c-a)/2;
14. int C = b + (b-a);
16. //a mein dikkat
17. if(A!=0 && A>=a && A%a==0) cout<<"YES\n";
19. //b mein dikkat
20. else if(B && B>=b && B%b==0 && (c-a)%2==0) cout<<"YES\n";
21.  
22. //c mein dikkat
23. else if(C && C>=c && C%c==0) cout<<"YES\n";
24.  
25. //kuch nhi ho skta
26. else cout<<"NO\n";
28. }
29. }

21. Two-gram

1. #include<bits/stdc++.h>
2. using namespace std;
3.  
4. int main(){
6. int n, mc=0; //max count mc
7. string s, ss, twogram; //substring ss
8. map<string, int> smp; //string map smp
10. cin>>n>>s;
12. for(int i=0; i<n-1; i++){
13. ss = s[i], ss+=s[i+1], smp[ss]++; //AB:1
14. if(smp[ss]>mc) mc=smp[ss], twogram=ss;
15. }
17. cout<<twogram;
18. }

20. Business trip

1. #include<bits/stdc++.h>
2. using namespace std;
3. int main(){
4. int k, cnt=0, a[12]; //12 months
5. cin>>k;
6. for(int i=0; i<12; i++) cin>>a[i];
7. sort(a, a+12);
8. for(int i=11; i>=0; i--){
9. if(k<=0) { cout<<cnt; return 0;}
10. k-=a[i];
11. cnt++;
12. }
13. cout<<(k<=0?cnt:-1); return 0;
14. }

19. Case of the Zeros and Ones

1. #include<bits/stdc++.h>
2. using namespace std;
3.  
4. int main(){
5. int n, cnt=0;
6. char c; cin>>n;
7. while(n--){
8. cin>>c;
9. if(c=='1') cnt++;
10. else cnt--;
11. }
12. cout<<abs(cnt);
13. }

18. Construct the String

1. #include<bits/stdc++.h>
2. using namespace std;
3. int main(){
4. int t; cin>>t;
5. while(t--){
6. string s;
7. int n, a, b;
8. cin>>n>>a>>b;
9. for(int i=0; i<b; i++) s+='a'+i;
10. for(int i=0; i<a-b; i++) s+=s[i];
11. for(int i=0; i<n-a; i++) s+=s[i];
12. cout<<s<<endl;
14. }
15. }

17. Keyboard

1. #include<bits/stdc++.h>
2. using namespace std;
3.  
4. int main(){
5. char c,i; cin>>c;
6. string s = "qwertyuiopasdfghjkl;zxcvbnm,./";
7. while(cin>>i){
8. cout<<s[s.find(i)-(c=='R')+(c=='L')];
9. }
10. return 0;
11. }

16. Vasya and Socks

1. #include<bits/stdc++.h>
2. using namespace std;
3.  
4. int main(){
5. int n, m, days=0;
6. cin>>n>>m;
7. for(int i=1; i<=n; i++){
8. if(i%m == 0) n++;
9. days++;
10. }
11. cout<<days;
12. }

15. Multiply by 2, divide by 6

1. #include<bits/stdc++.h>
2. using namespace std;
3. typedef long long ll;
4. int main(){
5. ll n, cnt, t;
6. cin>>t;
7. while(t--){
8. cin>>n;
9. cnt = 0;
10. while(n%6==0) n/=6, cnt+=1;
11. while(n%3==0) n/=3, cnt+=2;
12. if(n!=1) cnt=-1;
14. cout<<cnt<<endl;
16. }
17. }

14. New Year's Number

1. #include<bits/stdc++.h>
2. using namespace std;
3.  
4. void solve(){
5. long long int n,x,y; cin>>n;
7. for(x=0; x<=1000; x++){
8. y = n - (2020*x);
9. if(y<0) break;
11. else if(y%2021==0)
12. {
13. cout<<"YES"<<endl;
14. return;
15. }
17. else continue;
18. }
20. cout<<"NO"<<endl;
22. }
23.  
24. int main(){
25. int t; cin>>t;
26. while(t--){
27. solve();
28. }
29. }

13. Candies

1. #include<bits/stdc++.h>
2. using namespace std;
3.  
4. int main(){
5. int t; cin>>t;
6. while(t--){
7. int n, x; cin>>n;
8. for(int k=2; k<=30; k++)
9. {
10. int dr = pow(2,k)-1;
11. if(n%dr) continue;
12. x = n/dr;
13. break;
14. }
15. cout<<x<<endl;
16. }
17. }

12. Sale

1. #include<bits/stdc++.h>
2. using namespace std;
3. int main(){
4. int n, m; cin>>n>>m;
5. int a[n], ans=0;
6. for(int i=0; i<n; i++) cin>>a[i];
7. sort(a,a+n);
8. for(int i=0; i<m; i++){
9. if(a[i]>=0) break;
10. ans += a[i];
11. }
12. cout<<abs(ans);
13. }

11. Odd Divisor

1. #include<bits/stdc++.h>
2. using namespace std;
3. typedef long long ll;
4. int main(){
5. int t; cin>>t;
6. while(t--){
7. ll n; cin>>n;
8. while(n%2==0) n/=2;
9. cout<<(n>1 ? "YES" : "NO")<<endl;
10. }
11. }

10. Ilya and Bank Account

1. #include<bits/stdc++.h>
2. using namespace std;
3. int main(){
4. int n; cin>>n;
5. if(n<0){
6. int no_ones = n/10;
7. int no_tens = n/100 * 10 + n%10;
8. cout<<max(no_ones, no_tens);
9. } else {
10. cout<<n;
11. }
12. }

9. Game With Sticks

1. #include<bits/stdc++.h>
2. using namespace std;
3. int main(){
4. int n,m;
5. cin>>n>>m;
6. if(min(n,m)%2) cout<<"Akshat";
7. else cout<<"Malvika";
8. }

8. Puzzles

1. #include<bits/stdc++.h>
2. using namespace std;
4. int main(){
5. int n,m; cin>>n>>m;
6. int a[m];
7. for(int i=0; i<m; i++) cin>>a[i];
8. sort(a,a+m);
9. int MIN = a[n-1]-a[0];
10. for(int i=1; i+n-1<m; i++)
11. MIN = min(MIN, a[i+n-1]-a[i]);
12. cout<<MIN;
13. }

7. Dubstep

1. #include<bits/stdc++.h>
2. using namespace std;
3. int main(){
4. string s; cin>>s;
5. int flag = 0;
7. for(int i=0; i<s.size(); i++){
9. if(s[i]=='W' && s[i+1]=='U' && s[i+2]=='B') {
10. if(flag==1) cout<<" ";
11. i += 2;
12. }
14. else cout<<s[i], flag=1;
15.  
16. }
17. }

6. Kefa and First Steps

1. #include<bits/stdc++.h>
2. using namespace std;
3.  
4. int main(){
5. int n; cin>>n;
6. int a[n], cnt=1, max=1;
7. for(int i=0; i<n; i++){
8. cin>>a[i];
9. }
10. for(int i=1; i<n; i++){
11. if(a[i]>=a[i-1]) {
12. cnt++;
13. if(max<cnt) max=cnt;
14. }
15. else cnt=1;
16. }
17. cout<<max;
18. }

5. Gravity Flip

1. #include<bits/stdc++.h>
2. using namespace std;
3.  
4. int main(){
5. int c,r;
6. vector<int> a;
7. cin>>c;
8.  
9. for(int i=0; i<c; i++){
10. cin>>r;
11. a.push_back(r);
12. }
13.  
14. sort(a.begin(), a.end());
15.  
16. for(int i=0; i<c; i++){
17. cout<<a[i]<<" ";
18. }
19.  
20. }

4. HQ9+

1. #include<bits/stdc++.h>
2. using namespace std;
3. int main(){
4. string s; cin>>s;
5. for(int i=0; i<s.size(); i++){
6. if(s[i]=='Q' || s[i]=='H' || s[i]=='9'){
7. cout<<"YES";
8. return 0;
9. }
10. }
11. cout<<"NO";
12. }

3. Even Odds

1. #include<bits/stdc++.h>
2. using namespace std;
3.  
4. int main(){
5. long long n,k;
6. cin>>n>>k;
7. n = (n+1)/2;
8. if(k<=n) cout<<2*k-1;
9. else cout<<(k-n)*2;
10. }

2. Twins

1. #include<bits/stdc++.h>
2. using namespace std;
3.  
4. int main(){
5. int n; cin>>n;
6. int a[n], sum=0, cnt=0, curr=0;
7.  
8. for(int i=0; i<n; i++) cin>>a[i], sum+=a[i];
9. sort(a,a+n);
10. sum/= 2;
11.  
12. for(int i=n-1; i>=0; i--){
13. curr+= a[i];
14. cnt++;
15. if(curr>sum) break;
16. }
18. cout<<cnt;
19. }

1. Football

1. #include<bits/stdc++.h>
2. using namespace std;
3.  
4. int main(){
5. string a; cin>>a;
6. int zero=0, one=0;
8. for(int i=0; i<size(a); i++){
10. cin>>a[i];
11. if(a[i] == '0') {zero++; one=0;}
12. else {one++; zero=0;}
13. if(one==7 || zero==7) {break;}
14. }
16. if(one==7 || zero==7) {cout<<"YES";}
17. else {cout<<"NO";}
18. }