【HDU1102】Constructing Roads（MST基础题）

最小生成树水题。prim一次AC

#include <iostream>
#include <cstring>
#include <cstdlib>
#include <cstdio>
#include <cctype>
#include <cmath>
#include <algorithm>
#include <numeric>

#define typec int
using namespace std;

const int V = 105;
const int inf = 0xffff;
int vis[V]; typec lowc[V];
int Map[105][105];

typec prim (typec cost[][V], int n) {
    int i, j, p;
    typec minc, res = 0;
    memset(vis, 0, sizeof(vis));
    vis[0] = 1;
    for (i = 1; i < n; ++ i) lowc[i] = cost[0][i];
    for (i = 1; i < n; ++ i) {
        minc = inf; p = -1;
        for (j = 0; j < n; ++ j) {
            if (0 == vis[j] && minc > lowc[j]) {
                minc = lowc[j]; p = j;
            }
        }
        if (inf == minc) return -1;
        res += minc; vis[p] = 1;
        for (j = 0; j < n; ++ j) {
            if (0 == vis[j] && lowc[j] > cost[p][j]) {
                lowc[j] = cost[p][j];
            }
        }
    }
    return res;
}

int main () {
    //cout << inf <<endl;
    int n;
    while (cin >> n) {
        for (int i = 0 ; i < n; ++ i) {
            for (int j = 0 ; j < n; ++ j) {
                scanf("%d", &Map[i][j]);
            }
        }
        int ok_line; cin >> ok_line;
        for (int i = 0; i < ok_line; ++ i) {
            int s, e;
            scanf("%d%d", &s, &e);
            Map[s - 1][e - 1] = Map[e - 1][s - 1] = 0;
        }
        cout << prim(Map, n) << endl;
    }
    return 0;
}