奇怪的卡常题

#include <cstdio>
#include <cstdint>
#include <algorithm>
using namespace std;

// 快速二进制 gcd，避免除法与取模
int fast_gcd(int a, int b) {
    if (a == 0) return b;
    if (b == 0) return a;
    int az = __builtin_ctz(a);
    int bz = __builtin_ctz(b);
    int shift = az < bz ? az : bz;
    a >>= az;
    b >>= bz;
    while (a != b) {
        if (a > b) {
            a -= b;
            a >>= __builtin_ctz(a);
        } else {
            b -= a;
            b >>= __builtin_ctz(b);
        }
    }
    return a << shift;
}

int a[2000], b[2000];

int main() {
    int n, m;
    scanf("%d%d", &n, &m);
    for (int i = 0; i < n; ++i) scanf("%d", &a[i]);
    for (int i = 0; i < m; ++i) scanf("%d", &b[i]);

    uint32_t ans = 0;
    for (int i = 0; i < n; ++i) {
        int ai = a[i];
        uint32_t ixor = (uint32_t)i;   // 提前转换，避免内层重复转换
        for (int j = 0; j < m; ++j) {
            int bj = b[j];
            int g;
            if (ai == 0) g = bj;
            else if (bj == 0) g = ai;
            else g = fast_gcd(ai, bj);
            ans += g ^ ixor ^ (uint32_t)j;
        }
    }
    printf("%u\n", ans);
    return 0;
}

...

、、

#include <stdio.h>
__attribute__((optimize("-O3"))) main(){for (;;) puts("傻逼");}