UVALive 5009

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The question：给出n组a，b，c的值，求出函数值最大值的最小值

Solution：三分，黄金分割法（优选法），Fibonacci搜索都可求单峰函数的极值。

Conclusion：跟据题目要求判断循环的次数或者需要控制的精度 Code：

#include <bits/stdc++.h>
using namespace std;
const double eps = 1e-9;
int n;
int a[10004], b[10004], c[10004];
double F(double x)
{
double ans = a[0] * x * x + b[0] * x + c[0];
for (int i = 1; i < n; i++)
{
ans = max(ans, a[i] * x * x + b[i] * x + c[i]);
}
return ans;
}
int main()
{
int T;
scanf("%d", &T);
while (T--)
{
scanf("%d", &n);
for (int i = 0; i < n; i++)
{
scanf("%d%d%d", &a[i], &b[i], &c[i]);
}
double L = 0.0, R = 1000.0;
double m1, m2;
while (R - L > eps)
{
m1 = L + (R - L) / 3.0;
m2 = R - (R - L) / 3.0;
if (F(m1) < F(m2))
R = m2;
else
L = m1;
}
printf("%.4f\n", F(L));
}
return 0;
}