ZOJ4070 Function and Function（良心签到题）

#include <bits/stdc++.h>

using namespace std;
const int f[10] = {1, 0, 0, 0, 1, 0, 1, 0, 2, 1};

int x, k;
int ans;
inline int update(int x) {
    int res = 0;
    while (x) {
        res += f[x%10];
        x /= 10;
    }
    return res;
}

int main()
{
    int T;
    cin >> T;
    while(T--) {
        scanf("%d%d", &x, &k);
        ans = x;
        while (k && ans > 1) {
            ans = update(ans);
            k--;
        }
        if (k > 0) {
            if (k % 2)
                ans = 1-ans;
        }
        printf("%d\n", ans);
    }
    return 0;
}
/*
6
123456789 1
888888888 1
888888888 2
888888888 999999999
98640 12345
1000000000 0
*/