hdu 5432 Pyramid Split（二分）

题目链接：hdu 5432 Pyramid Split

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

using namespace std;
const int maxn = 10005;
const double eps = 1e-4;

int N;
double A[maxn], B[maxn];

double judge(double h) {
double ret = 0;
for (int i = 0; i < N; i++) {
if (A[i] < h) continue;
double a = A[i] - h;
double b = a * B[i] / A[i];
ret += a * b * b;
}
return ret;
}

int main () {
int cas;
scanf("%d", &cas);
while (cas--) {
double l = 0, r = 0;
scanf("%d", &N);
for (int i = 0; i < N; i++) {
scanf("%lf", &A[i]);
r = max(r, A[i]);
}
for (int i = 0; i < N; i++) scanf("%lf", &B[i]);

double ans = judge(0) / 2;
while (fabs(r - l) > eps) {
double mid = (l + r) / 2;
if (judge(mid) > ans) l = mid;
else r = mid;
}
printf("%d\n", (int)l);
}
return 0;
}