UVa11136 Hoax or what

模拟水题.熟悉一下multiset的用法.

 1 #include <cstdio>
 2 #include <cstring>
 3 #include <iostream>
 4 #include <set>
 5 using namespace std;
 6 
 7 int N, K;
 8 multiset<int> S;
 9 
10 int main()
11 {
12     multiset<int>::iterator mx, mn;
13     while(cin>>N, N)
14     {
15         long long ans = 0;S.clear();
16         for(int i = 1, x; i <= N; i++)
17         {
18             cin>>K;
19             for(int j = 1; j <= K; j++) scanf("%d", &x), S.insert(x);
20             mn = S.begin();
21             mx = S.end(), mx--;
22             ans += (*mx - *mn);
23             S.erase(mx), S.erase(mn);
24         }
25         cout<<ans<<endl;
26     }
27     return 0;
28 }