POJ-1258 Agri-Net 最小生成树

#include <cstring>
#include <cstdlib>
#include <cstdio>
#include <algorithm>
using namespace std;

int N, pos, set[105];

struct Node
{
int x, y, dist;
bool operator < (Node t) const
{
return dist < t.dist;
}
}e[10005];

int find(int x)
{
return set[x] = x == set[x] ? x : find(set[x]);
}

void merge(int a, int b)
{
set[a] = b;
}

int main()
{
int c, cnt, ans;
while(scanf("%d", &N) == 1) {
pos = cnt = ans = 0;
for (int i = 1; i <= N; ++i) {
set[i] = i;
for (int j = 1; j <= N; ++j) {
scanf("%d", &c);
++pos;
e[pos].x = i, e[pos].y = j, e[pos].dist = c;
}
}
sort(e+1, e+1+pos);
for (int i = 1; i <= pos; ++i) {
int a = find(e[i].x), b = find(e[i].y);
if (a != b) {
merge(a, b);
ans += e[i].dist;
++cnt;
if (cnt == N-1) {
break;
}
}
}
printf("%d\n", ans);
}
return 0;
}