Extra-terrestrial Intelligence

Description
input
input.txt
output
output.txt
Recently Vasya got interested in finding extra-terrestrial intelligence. He made a simple extra-terrestrial signals’ receiver and was keeping a record of the signals for n days in a row. Each of those n days Vasya wrote a 1 in his notebook if he had received a signal that day and a 0 if he hadn’t. Vasya thinks that he has found extra-terrestrial intelligence if there is a system in the way the signals has been received, i.e. if all the intervals between successive signals are equal. Otherwise, Vasya thinks that the signals were sent by some stupid aliens no one cares about. Help Vasya to deduce from the information given by the receiver if he has found extra-terrestrial intelligence or not.

Input
The first line contains integer n (3 ≤ n ≤ 100) — amount of days during which Vasya checked if there were any signals. The second line contains n characters 1 or 0 — the record Vasya kept each of those n days. It’s guaranteed that the given record sequence contains at least three 1s.

Output
If Vasya has found extra-terrestrial intelligence, output YES, otherwise output NO.

Sample Input
Input
8
00111000
Output
YES
Input
7
1001011
Output
NO
Input
7
1010100
Output
YES
题意比较简单，题目比较水，直接给代码。

#include 
#include 
int main()
{
    int n, a[101];
    char xx[101];
    freopen("input.txt", "r", stdin);
    freopen("output.txt", "w", stdout);
    while(~scanf("%d", &n))
    {
        memset(a, 0, sizeof(a));
        int t = 0, j = 0;
        scanf("%s", xx);
        for(int i = 0; i < n; i++)
        {
            if(xx[i] == '1')
            {
                t = i;
                break;
            }
        }
        for(int i = t  + 1;  i < n; i++)
        {
            if(xx[i] == '1')
            {
                a[j++] = i - t;
                t = i;
            }
        }
        int fl = 0;
        for(int i = 1;  i < j; i++)
        {
            if(a[i] != a[i - 1])
            {
                fl = 2;
                break;
            }
        }
        if(fl) puts("NO");
        else puts("YES");
    }
    return 0;
}