#include<stdio.h>#include<set>#include<algorithm>using namespace std;set <int> s; set <int> ::iterator it;int band[105][105], price[105][105], m[105];int main() { int T, n, i, j; scanf("%d",&T); while(T--) { scanf("%d",&n); s.clear(); for(i = 0; i < n; i++) { scanf("%d",&m[i]); for(j = 0; j < m[i]; j++) { scanf("%d%d",&band[i][j], &price[i][j]); s.insert(band[i][j]); } } double rate = 0; for(it = s.begin(); it != s.end(); it++) { int k = *it, sum_price = 0; for(i = 0; i < n; i++) { int min_price = 0x3fffff; for(j = 0; j < m[i]; j++) { if(band[i][j] >= k && price[i][j] < min_price) { min_price = price[i][j]; } } sum_price += min_price; } if(k * 1.0 / sum_price > rate) rate = k * 1.0 / sum_price; } printf("%.3lfn",rate); } return 0;}
