ACM第四站————最小生成树（克鲁斯卡尔算法）

#include <cstdio>
#include <cstring>
#include <algorithm>
#define MAXN 22
using namespace std;
int map[MAXN][MAXN], n;
int p[MAXN];
struct Edge {
    int begin, end, weight;
    bool operator < (const Edge& a) const {
        return weight < a.weight;
    }
}edges[MAXN];
int Find(int *p, int f) { while ( p[f] > 0 ) f = p[f];   return f; }
void Dijkstra()
{
    int tim = 0;
    for (int i = 0; i < n; i ++)
        for (int j = i+1; j < n; j ++) {
            if ( map[i][j] ) {
                edges[tim].begin = i;
                edges[tim].end = j;
                edges[tim].weight = map[i][j];
                ++ tim;
            }
        }
    sort(edges, edges+tim);
    memset(p, 0, sizeof(p));
    int sum = 0;
    for (int i = 0; i < tim; i ++) {
        int x = Find(p, edges[i].begin);
        int y = Find(p, edges[i].end);
        if ( x != y ) {
            p[x] = y;
            sum += edges[i].weight;
        }
    }
    printf("%d\n", sum);
}
int main(void)
{
    int T;
    scanf("%d", &T);
    while ( T -- ) {
        scanf("%d", &n);
        for (int i = 0; i < n; i ++)
            for (int j = 0; j < n; j ++) scanf("%d", &map[i][j]);
        Dijkstra();
    }
    return 0;
}