A. Two Substrings哈希表

Posted 2022-03-22 辉小歌

#include<bits/stdc++.h>
using namespace std;
map<string,int>mp;
int main(void)

    string s; cin>>s;
    bool flag=0;
    for(int i=0;i<s.size()+1;i++)
    
        if(s[i]=='A'&&s[i+1]=='B') 
        
            if(mp.count("AB")==0) mp["AB"]=i;
            if(mp.count("BA"))
            
                int t=mp["BA"];
                if(t+1!=i) flag=1;
            
        
        if(s[i]=='B'&&s[i+1]=='A')
        
            if(mp.count("BA")==0) mp["BA"]=i;
            if(mp.count("AB"))
            
                int t=mp["AB"];
                if(t+1!=i) flag=1;
            
        
    
    if(flag) puts("YES");
    else puts("NO");
    return 0;