摘要： 枚举左边两个数的和以及右边两个数的和，用二分查找将其配对并计数。Hash的方法晚点再写。/*Accepted 49208K 5188MS C++ 1146B 2012-05-04 23:56:30 */#include<cstdio>#include<cstring>#include<cstdlib>#include<algorithm>using namespace std;#define MAXN 4005/*int cmp( const void *_p, const void *_q){ int *p = ( int *)_p; int 阅读全文