Codeforces Round #426 (Div. 2)B. The Festive Evening

 1 #include<bits/stdc++.h>
 2 using namespace std;
 3 
 4 int l[30],r[30];
 5 int b[30];
 6 
 7 int main(){
 8     int n,m; string s;
 9     cin>>n>>m;
10     cin>>s;
11     for(int i=s.size()-1;i>=0;i--){
12         if(r[s[i]-‘A‘]==0) {
13              r[s[i]-‘A‘]=i;
14         }
15 
16     }
17     memset(l,-1,sizeof(l));
18     for(int i=0;i<s.size();i++){
19         if(l[s[i]-‘A‘]==-1){
20             l[s[i]-‘A‘]=i;
21         }
22 
23     }
24 
25     int Max=0;
26     for(int i=0;i<s.size();i++){
27 
28         if(l[s[i]-‘A‘]==i){
29             Max++;
30             if(Max>m) {
31                 cout<<"YES"<<endl;return 0;
32             }
33         }
34         if(r[s[i]-‘A‘]==i){
35             Max--;
36         }
37         if(Max>m) {
38                 cout<<"YES"<<endl;return 0;
39             }
40 
41     }
42     cout<<"NO"<<endl;return 0;
43 }