UESTC 375

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传送门 : UESTC 375

code:

#include <cstdio>#include <cstring>#include <cmath>#include <algorithm>using namespace std;typedef double ld;const int N = 1010;int n;int data[N], sum[N], sum2[N];ld tmp[N], aver[N];ld cal(int x){aver[x] = (ld)sum[x] / x;return (ld)(sum[n] - sum[x]) / (n - x) - aver[x];}int main(){//freopen("in.txt", "r", stdin);int t;scanf("%d", &t);for(int cas = 1; cas <= t; ++cas){scanf("%d", &n);sum[0] = 0;sum2[0] = 0;for(int i = 1; i <= n; ++i)scanf("%d", data + i);sort(data + 1, data + n + 1);for(int i = 1; i <= n; ++i) sum[i] = sum[i - 1] + data[i], sum2[i] = sum2[i - 1] + data[i] * data[i];for(int i = 1; i < n; ++i) tmp[i] = cal(i);ld mx = -1e10;for(int i = 1; i < n; ++i) mx = max(mx, n * tmp[i] * tmp[i] - sum[i] * aver[i] - (sum[n] - sum[i]) * (aver[i] + tmp[i]));printf("Case #%d: %.6lf\n", cas, mx + sum2[n]);}return 0;}

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