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  1. #include <bits/stdc++.h>
  2. using namespace std;
  3.  
  4. int main() 
  5. {
  6.     int n;
  7.     cin>>n;
  8.  
  9.     string s;
  10.     cin>>s;
  11.  
  12.     int k;
  13.     cin>>k;
  14.  
  15.     int i=0; // Left pointer
  16.     int count = 0;
  17.     // store each character and its frequency in the map 
  18.     unordered_map<char,int>mp;
  19.     for(int j=0; j<n; j++) // 'j' Right pointer
  20.     {
  21.         mp[s[j]] = mp[s[j]] + 1; // increment the current character and store its frequency in map
  22.  
  23.         // If the distint charcter i mean greater than 'k'
  24.         //shrink the window from left
  25.         while(mp.size()>=k) // mp.size() means entire string chi frequency
  26.         {
  27.             mp[s[i]] = mp[s[i]] - 1; // remove that element
  28.  
  29.             // Remove the character from the map
  30.             // if its frequency becomes zero
  31.             if(mp[s[i]]==0)
  32.             {
  33.                 mp.erase(s[i]);
  34.             }
  35.  
  36.             count = count + (n-j); // then count the substrings
  37.             i++; // move the left pointer ahead 
  38.         }
  39.     }
  40.     cout<<count;
  41. }
Success #stdin #stdout 0s 5324KB
comments (?)
stdin 
5
abcca
3
stdout 
4
https://ideone.com/UaVUT9
language:
C++ (gcc 8.3)
created:
3 hours ago
visibility:
public

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