A - Two Substrings
You are given string s. Your task is to determine if the given strings contains two non-overlapping substrings "AB" and "BA" (the substrings can go in any order).
Input
The only line of input contains a string s of length between1 and 105 consisting of uppercase Latin letters.
Output
Print "YES" (without the quotes), if strings contains two non-overlapping substrings "AB" and "BA", and "NO" otherwise.
Example
INPUT
ABA
OUTPUT
NO
INPUT
BACFAB
OUTPUT
YES
INPUT
AXBYBXA
OUTPUT
NO
Note
In the first sample test, despite the fact that there are substrings "AB" and "BA", their occurrences overlap, so the answer is "NO".
In the second sample test there are the following occurrences of the substrings:BACFAB.
In the third sample test there is no substring "AB" nor substring "BA".
给出一行字符，判断是否出现两个不重叠的字串“AB”和“BA”
思路：
暴力解就是了，看到标签是DP想了半天。最后发现直接用C++的find函数即可
#include<bits/stdc++.h>
using namespace std;
int main(){
string s;
cin >> s;
int a = s.find("AB");
int b = s.find("BA");
if (a != -1 && s.find("BA", a + 2) != -1 || b != -1 && s.find("AB", b + 2) != -1)
cout << "YES";
else
cout << "NO";
}