hdoj1874 畅通工程续

来源：互联网发布：优化农村干部队伍结构编辑：程序博客网时间：2024/06/11 15:47

题目链接：http://acm.hdu.edu.cn/showproblem.php?pid=1874

Dijsktra算法：

伪代码：

清除所有标记

d[0] = 0, 其他d[i] = intmax

for (1到n) {

所有没有标记的点中寻找d[i]最小的点x

标记x

对以x出发的点进行更新所有边（x,y) 即：d[y] = min( d[y], d[x]+map[x][y] )

}

//Dijkstra算法的应用#include <iostream>using namespace std;const int MAX = 201;const int intmax = 10000000;int Map[MAX][MAX];int dist[MAX];bool visited[MAX];int n, m, s, e;int i, j;void Dijsktra(){for (i = 0; i < n; i++) dist[i] = Map[s][i];dist[s] = 0;visited[s] = 1;for (i = 0; i < n; i++) {int x = s, m = intmax;for (j = 0; j < n; j++) if (!visited[j] && dist[j]<=m)m = dist[x=j];visited[x] = 1;for (j = 0; j < n; j++) {//更新dist[j] = min(dist[j], dist[x]+Map[x][j]);}}}int main(){int a, b, cost;while (cin >> n >> m) {for (i = 0; i < n; i++)for (j = 0; j < n; j++) {if (i == j) Map[i][j] = 0;else Map[i][j] = intmax;}for (i = 0; i < m; i++) {cin >> a >> b >> cost;if (cost < Map[a][b]) {//要处理重路Map[a][b] = cost;Map[b][a] = cost;}}cin >> s >> e;//起点和终点memset (visited, 0, sizeof(visited));for (i = 0; i < MAX; i++)dist[i] = intmax;Dijsktra();if (dist[e] == intmax) cout << -1 << endl;else cout << dist[e] << endl;}return 0;}