【HDOJ】2721 Persistent Bits

题目有点长，但是题意说的很清楚。位操作。

#include <stdio.h>

int nums[65540];

int main() {
    int a, b, c, s;
    int i, j, k, n, tmp, mask;

    while (scanf("%d", &a)!=EOF && a) {
        scanf("%d%d%d", &b, &c, &s);
        n = mask = 0;
        nums[n++] = tmp = s;
        a = a%c;
        b = b%c;
        for (j=0; j<65537; ++j) {
            tmp = (a*tmp + b) % c;
            if (tmp == s)
                break;
            nums[n++] = tmp;
            k = tmp ^ s;
            mask |= k;
            if (mask == 0xffff)
                break;
        }
        j = 0x8000;
        for (i=0; i<16; ++i) {
            tmp = (j>>i);
            k = tmp & s;
            tmp &= mask;
            if (tmp)
                printf("?");
            else {
                if (k)
                    printf("1");
                else
                    printf("0");
            }
        }
        printf("\n");
    }

    return 0;
}