11346-probability (probability)

Link to the question: Ultraviolet A 11346-Probability

Given the range of X and Y, and s, the probability that the area of the image formed by X and Y axes is larger than S is given.

Solution: first, the Equation xy ≥ s, that is, y = s/X.

The area of S2 is calculated using credits. The original function of Y = s/X is lnx.
So S2 = s? (LN ()? Ln (x ))

#include <cstdio>#include <cstring>#include <cmath>#include <algorithm>using namespace std;int main  () {    int cas;    double a, b, s;    scanf("%d", &cas);    while (cas--) {        scanf("%lf%lf%lf", &a, &b, &s);        double r = min(s / b, a);        double ans = r * b + log(a) * s;        if (fabs(s) > 1e-9)            ans = ans - log(r) * s;        double p = 1 - ans / (a * b);        printf("%.6lf%c\n",  fabs(p * 100), ‘%‘);    }    return 0;}