BZOJ4236 JOIOJI(map)

 1 #include<bits/stdc++.h>
 2 using namespace std;
 3 int main()
 4 {
 5     int n;
 6     cin>>n;
 7     string s;
 8     cin>>s;
 9     int J=0,O=0,I=0;
10     map<pair<int,int>,int>mapp;
11     mapp[make_pair(0,0)]=-1;
12     int ans=0;
13     for(int i=0;i<n;i++){
14         if(s[i]==‘J‘) J++;
15         if(s[i]==‘O‘) O++;
16         if(s[i]==‘I‘) I++;
17         if(mapp.find(make_pair(J-O,O-I))==mapp.end()){
18             mapp[make_pair(J-O,O-I)]=i;
19         }
20         else{
21             ans=max(ans,i-mapp[make_pair(J-O,O-I)]);
22         }
23     }
24     cout<<ans<<endl;
25     return 0;
26 }