MLE： 找出出现偶数次的那个数

位标记，MLE了

/* csu 1069 changelong MLE */
# include <stdio.h>
# define MAX 10000000
# define INDEX(x) ((x)>>(3))
# define OFFSET(x) ((x)%(8))
# define GET_BIT(x) (vis[INDEX(x)]>>OFFSET(x) & 0x1)
# define SET_BIT(x) (vis[INDEX(x)] |= (char)((0x1)<<OFFSET(x)))

char vis[INDEX(MAX)+1];　　　　// 导致MLE的元凶

int main()
{
    int T, n, p, q;
    int x, i, j, ans;

    freopen("in.txt", "r", stdin);
    freopen("out.txt", "w", stdout);

    scanf("%d", &T);
    for (i = 1; i <= T; ++i)
    {
        ans = 0;
        scanf("%d%d%d", &n, &p, &q);
        if (q%2 == 1)
            for (j = 0; j < n; ++j, ans ^= x)
                scanf("%d", &x);
        else
            for (j = 0; j < n; ++j)
            {
                scanf("%d", &x);
                ans ^= x;
                SET_BIT(x);
                if (!GET_BIT(x)) ans ^= x;
            }
        printf("Case %d:\n%d\n", i, ans);
    }

    return 0;
}