UVALive 3635 Pie 切糕大师 二分
题意：为每个小伙伴切糕，要求每个小盆友（包括你自己）分得的pie一样大，但是每个人只能分得一份pie，不能拿两份凑一起的。
做法：二分查找切糕的大小，然后看看分出来的个数有没有大于小盆友们的个数，它又没说每个pie都要分完，分不完的留给工作人员吃嘛。
代码：
/** Author: illuz <iilluzen[at]gmail.com>* Blog: http://blog.csdn.net/hcbbt* File: live3652.cpp* Create Date: 2013-09-10 00:40:36* Descripton: binary, greedy */#include <cstdio>#include <cmath>#include <cstdlib>#include <algorithm>using namespace std;const int MAXN = 10010;const double PI = acos(-1.0);int n, f, t;double a[MAXN], Max;bool judge(double x) {int sum = 0;for (int i = 0; i < n; i++)sum += a[i] / x;if (sum >= f + 1) return true;return false;}int main() {scanf("%d", &t);while (t--) {scanf("%d%d", &n, &f);for (int i = 0; i < n; i++) {scanf("%lf", &a[i]);a[i] = PI * a[i] * a[i];Max = max(Max, a[i]);}double low = 0, mid;while (Max - low > 1e-5) {mid = low + (Max - low) / 2;if (judge(mid)) low = mid;else Max = mid;}printf("%.4lf\n", low);}return 0;}