// 严格按照题目来
#include <stdio.h>
#include <stdlib.h>
#include <math.h>
#include <algorithm>
using namespace std;

const int p = 10000;
double xs, ys;
int x, y, ans;

int main(void)
{
    scanf ("%lf%lf", &xs, &ys);
    ans = 1, x = y = 0;
    // 严格按照题目来 (more than ... ; less than ... )
    ys -= 1E-10, xs += 1E-10;
    while (x == y)
          ans++, x = int (ans * xs) / 100, y = int (ans * (ys)) / 100;
    printf ("%d", ans);
    return 0;
}

想知道为什么ys是减1E-10，而xs是加1E-10！

想知道为什么ys是减1E-10，而xs是加1E-10！

because it said "more than P%" and "less than Q%", so it can't be equal, you have to shorten interval, just add or sub 1E-10
（因为题目是说“more than P%” 和 “less than Q%”，因此不能相等，所以两边的区间都要往里面再缩小一点，只要加或减1E-10就行）