SCU2016-05 E题二分

Analyse:
就是二分+贪心判断，强行加eps不要。。

/**********************jibancanyang************************** *Author*        :jibancanyang *Created Time*  : 三  7/13 09:56:34 2016**Problem**:**Get**:**Code**:***********************[e-mail]**********************/#include <cstdio>#include <cstring>#include <iostream>#include <algorithm>#include <vector>#include <queue>#include <set>#include <map>#include <string>#include <cmath>#include <cstdlib>#include <ctime>#include <stack>using namespace std;typedef pair<int, int> pii;typedef long long ll;typedef unsigned long long ull;typedef vector<int> vi;#define pr(x) cout << #x << ": " << x << "  " #define pl(x) cout << #x << ": " << x << endl;#define pri(a) printf("%d\n",(a))#define xx first#define yy second#define sa(n) scanf("%d", &(n))#define sal(n) scanf("%lld", &(n))#define sai(n) scanf("%I64d", &(n))#define vep(c) for(decltype((c).begin() ) it = (c).begin(); it != (c).end(); it++) const int mod = int(1e9) + 7, INF = 0x3f3f3f3f;const int maxn = 1e4 + 13;int n, f;int pie[maxn];double pi = acos(-1), eps = 1e-7;bool judge(double mid) {    int sum = 0;    for (int i = 0; i < n; i++) {        int te = double(pie[i]) * pie[i] * pi / mid;        sum += te;    }    return sum >= f;}int main(void){#ifdef LOCAL    freopen("in.txt", "r", stdin);    //freopen("out.txt", "w", stdout);#endif    int T; sa(T);    while (T--) {        sa(n), sa(f);        f++;        for (int i = 0; i < n; i++) sa(pie[i]);        double l = 0, r = 1e10;        for (int i = 0; i < 250; i++) {            double mid = (l + r) / 2;            if (judge(mid)) {                l = mid + eps;            } else r = mid - eps;        }        printf("%.4f\n", l);    }    return 0;}