CF1168B Good Triple 性质分析_好题

#include<bits/stdc++.h>
#define maxn 1000000 
#define setIO(s) freopen(s".in","r",stdin) 
using namespace std;
int n; 
char str[maxn]; 
int main(){
   //  setIO("input"); 
    int r; 
    scanf("%s",str+1),n=strlen(str+1),r=n+2; 
    long long ans=0; 
    for(int i=n-1;i>=1;--i){
        for(int j=1;i+2*j<=n;++j) {
            if(str[i]==str[i+j]&&str[i+j]==str[i+2*j]) 
            {
                r=min(r,i+2*j); 
                break; 
            } 
        }
        ans += (long long)max(n-r+1,0); 
    }
    cout<<ans<<endl; 
    return 0; 
}