888C - K-Dominant Character - CodeForces Solution

#include<bits/stdc++.h>
using namespace std;


bool f(int k,string& s){

   
   for(int i=0;i<=25;i++){
    vector<int> freq(26,0);
    bool f=true;
    for(int j=0;j<k;j++){
        freq[s[j]-'a']++;
    }
    if(freq[i]==0) f=false;
    int start=0;
    int end=k-1;
    while(end<=s.size()-1){
        freq[s[start]-'a']--;
        start++;
        end++;
        if(end<s.size()){
            freq[s[end]-'a']++;
            if(freq[i]==0) f=false;
        }
    }
    if(f) return true;




   }

  return false;




}




int main(){

 string s="";
 cin>>s;
 int low=0;
 int high=s.size();
 int ans=-1;
 while(low<=high){
    int mid=(low+high)/2;
    if(f(mid,s)) high=mid-1,ans=mid;
    else low=mid+1;
 }
 cout<<ans<<endl;
 
}