还是畅通工程 HDU - 1233

#include<iostream>
#include<cstdio>
#include<cstdlib>
#include<cstring>
#include<cmath>
#include<set>
#include<stack>
#include<queue>
#include<algorithm>
// cout << "  ===  " << endl;

using namespace std;
typedef long long ll;
const int maxn = 100 + 7, INF = 0x3f3f3f3f, mod = 1e9+7;
int n, m, x, y, d;
int a[maxn][maxn], vis[maxn];

void init() {
memset(vis, 0, sizeof vis);
memset(a, INF, sizeof a);
for(int i = 0; i < m; ++i) {
scanf("%d%d%d", &x, &y, &d);
a[x][y] = a[y][x] = d;
}
}

void prim() {
vis[1] = 1;
int ans = 0;
while(1) {
int v = -1;
for(int i = 2; i <= n; ++i) {
if(!vis[i] && (v == -1 || a[1][v] > a[1][i])) v = i;
}
if(v == -1) break;
ans += a[1][v]; vis[v] = 1;
for(int i = 1; i <= n; ++i)
a[1][i] = min(a[v][i], a[1][i]);
}
cout << ans << endl;
}

int main() {
while(scanf("%d", &n) != EOF && n) {
m = n * (n-1) / 2;
init();
prim();
}
return 0;
}