[模拟]位运算实现四则运算

const int mod = 1000;

int bitpow(int x, int n) {
    int ans = 1;
    int t = x;
    while(n) {
        if(n & 1) {
            ans = (ans * t) % mod;
        }
        t = t * t % mod;
        n >>= 1;
    }
    return ans;
}

int bitadd(int x, int y) {
    int xr = x ^ y;
    int nd = x & y;
    while(nd) {
        int xr1 = xr;
        int nd1 = nd << 1;
        xr = xr1 ^ nd1;
        nd = xr1 & nd1;
    }
    return xr;
}

int negtive(int x) {
    return bitadd(~x, 1);
}

int bitminus(int x, int y) {
    return bitadd(x, negtive(y));
}

int bitmulti(int x, int y) {
    int ans = 0;
    while(y) {
        if(y & 1) {
            ans = bitadd(ans, x);
        }
        x = (x << 1);
        y = (y >> 1);
    }
    return ans;
}

int bitdiv(int x, int y) {
    int ans = 0;
    for(int i = 31; i >= 0; i--) {
        if((x>>i) >= y) {
            ans += (1<<i);
            x -=(y<<i);
        }
    }
    return ans;
}