Codeforces Round #306 (Div. 2)——A——Two Substrings

#include<cstdio>
#include<algorithm>
#include<cstring>
using namespace std;
int main()
{
    char a[100110];
    while(~scanf("%s",&a)){
        int n = strlen(a);
        int t1 ,t2 ;
        t1 = t2 = 0;
        int i = 0;
        while(i < n){
            if(a[i] == ‘A‘ && a[i+1] == ‘B‘&&t1 == 0){
            t1++;
            i++;}
            else if(a[i] == ‘B‘ && a[i+1] == ‘A‘&&t2 == 0){
            t2++;
            i++;
            }
            i++;
        }
        if(t1 > 0 && t2 > 0){
            printf("YES\n");
            continue;
        }
         i = n-1;
        t1 = t2 = 0;
        while(i >= 0){
            if(a[i] == ‘A‘ && a[i+1] == ‘B‘&& t1 == 0){
                t1++;
                i--;
            }
            else if(a[i] == ‘B‘ && a[i+1] == ‘A‘ && t2 == 0){
                t2++;
                i--;
            }
            i--;
        }
        if(t1 > 0 && t2 > 0)
        printf("YES\n");
        else printf("NO\n");
        }
    return 0;
}