UVa 10673 - Play with Floor and Ceil

扩展欧几里得算法，直接套模板即可。

代码如下：

#include <cstdio>
#include <cmath>
#include <cstring>

void gcd(int a, int b, long long &d, long long &x, long long &y)
{
    if(!b)
    {
        d = a;
        x = 1;
        y = 0;
    }
    else
    {
        gcd(b, a%b, d, y, x);
        y -= x*(a/b);
    }
}
int main()
{
#ifdef test
    freopen("sample.txt", "r", stdin);
#endif
    int a, b, t;
    long long p, q, ans;
    double x, k;
    scanf("%d", &t);
    while(t--)
    {
        scanf("%lf%lf", &x, &k);
        a = floor(x/k);
        b = ceil(x/k);
        gcd(a, b, ans, p, q);
        ans = (int)x / ans;
        printf("%lld %lld\n", p*ans, q*ans);
    }
    return 0;
}