尺取法 C - Vasya and String CodeForces - 676C

C - Vasya and String

  CodeForces - 676C 

#include<iostream>
using namespace std;
int main()
{
    long long k,n;
    cin>>n>>k;
    string str;
    cin>>str;
    long long p=0,ans=0,s=0;
    for(int i=0;i<n;++i)
    {
        if(str[i]=='b') 
        ++p;
        while(p>k)
        {
            if(str[s++]=='b') --p;
        }
        ans=max(ans,i-s+1);
    }
    p=0;
    s=0;
    for(int i=0;i<n;++i)
    {
        if(str[i]=='a')
        ++p;
        while(p>k)
        {
            if(str[s++]=='a') --p;
        }
        ans=max(ans,i-s+1);
    }
    cout<<ans;
    return 0;
}

尺取法详解：https://blog.csdn.net/lxt_lucia/article/details/81091597