ACM--字符串--Two Substrings--水

题目地址：传送门

D - Two Substrings

Time Limit:2000MS     Memory Limit:262144KB     64bit IO Format:%I64d
& %I64u

Submit Status

Description

You are given string s. Your task is to determine if the given string s 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 between 1 and 10⁵ consisting
of uppercase Latin letters.

Output

Print "YES" (without the quotes), if string s contains two non-overlapping substrings "AB" and "BA",
and "NO" otherwise.

Sample Input

Input

ABA

Output

NO

Input

BACFAB

Output

YES

Input

AXBYBXA

Output

NO

Hint

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".

题解：这里可以使用strstr()函数，需要<string.h>头文件

#include<iostream>
#include<stdio.h>
#include<string.h>
using namespace std;
char s[100001];
int main(){
   char *c;
   scanf("%s",&s);
   if((c=strstr(s,"AB"))!=NULL&&strstr(c+2,"BA")!=NULL){
        printf("YES\n");
        return 0;
   }
   if((c=strstr(s,"BA"))!=NULL&&strstr(c+2,"AB")!=NULL){
        printf("YES\n");
        return 0;
   }
   printf("NO\n");
}