zzuli 1728 Problem D: 社交网络(概率论）@

Problem D: 社交网络

Time Limit: 2 Sec   Memory Limit: 128 MB Submit: 223   Solved: 60 Submit Web Board

Description

 

Input

Output

Sample Input

2 2 1 0 1 1 0 3 1 0 1 1 1 0 1 1 1 0

Sample Output

0.500 1.125

HINT

#include <iostream> #include <cstdio> #include <cstring> #include <cmath> #include <string> #include <algorithm> #include <vector> #include <map> using namespace std; const int N = 100010; typedef long long LL; int vis[40][40], c[35][35]; int n, k; int p[40]; int main() { memset(c,0,sizeof(c)); for(int i=0; i<=32; i++) c[i][0]=c[i][i]=1; for(int i=1; i<=31; i++) { for(int j=1; j<i; j++) { c[i][j]=c[i-1][j]+c[i-1][j-1]; } } int t, x; scanf("%d", &t); while(t--) { memset(p,0,sizeof(p)); scanf("%d %d",&n, &k); for(int i=1; i<=n; i++) { for(int j=1; j<=n; j++) { scanf("%d", &x); p[i]+=x; } } double sum=0; for(int i=1; i<=n; i++) for(int j=k;j<=p[i];j++) sum=sum+(1.0*c[p[i]][j]/(1<<p[i]))/2;//统计一个人满足交际花条件的概率*1 printf("%.3f\n",sum); } return 0; }