uva 11136 multiset

用multiset模拟一下就可以了，需要注意的是erase(val)会将值等于val的全部删掉，而erase(iterator)只会删去该iterator指向的一个值。

#include <iostream>
#include <cstring>
#include <cstdio>
#include <set>
using namespace std;

multiset<int> s;
multiset<int>::iterator it;

int main ()
{
    int n;
    while ( scanf("%d", &n), n )
    {
        long long sum = 0;
        s.clear();
        for ( int i = 0; i < n; i++ )
        {
            int m;
            scanf("%d", &m);
            while ( m-- )
            {
                int tmp;
                scanf("%d", &tmp);
                s.insert(tmp);
            }
            it = s.begin();
            int lb = (*it);
            s.erase(it);
            it = s.end();
            it--;
            int ub = (*it);
            s.erase(it);
            sum += ub - lb;
        }
        printf("%lld
", sum);
    }
    return 0;
}