UVALive-7509-Dome and Steles

ACM模版

描述

题解

找到一篇不错的题解，写的十分详细，三分。

twh233’s blog，有详细的图解，我就不转述了。毕竟，懒。

代码

#include <iostream>#include <algorithm>#include <cmath>using namespace std;const int MAXN = 1e5 + 10;const double EPS = 1e-14;template <class T>inline void scan_d(T &ret){    char c;    ret = 0;    while ((c = getchar()) < '0' || c > '9');    while (c >= '0' && c <= '9')    {        ret = ret * 10 + (c - '0'), c = getchar();    }}int n;double w[MAXN];double calc(double x){    double x1 = x, x2 = 1 - x;    if (x1 > x2)    {        swap(x1, x2);    }    double ans = w[n] + x2 * x2;    for (int i = 1; i < n; i++)    {        if (i & 1)        {            x1++;            ans = max(ans, w[n - i] + x1 * x1);        }        else        {            x2++;            ans = max(ans, w[n - i] + x2 * x2);        }    }    return sqrt(ans);}int main(){    int T;    scan_d(T);    for (int ce = 1; ce <= T; ce++)    {        printf("Case #%d: ", ce);        scan_d(n);        double a, b;        for (int i = 1; i <= n; i++)        {            scanf("%lf%lf", &a, &b);            if (a > b)            {                swap(a, b);            }            w[i] = a * a + (b / 2) * (b / 2);        }        sort(w + 1, w + n + 1);        double l = 0, r = 1;        while (l < r)        {            double m = (l + r) / 2;            double _m = (m + r) / 2;            if (calc(_m) < calc(m))            {                l = m + EPS;            }            else            {                r = _m - EPS;            }        }        printf("%.10f\n", calc(l));    }    return 0;}