HDU 1874 畅通工程续（Dijkstra算法求最短路径）

#include <iostream>
#include <cstdio>
#include <algorithm>
#include <cstring>
using namespace std;
const int N = 210;
const int INF = 1 << 30;
int n, m;
int map

, vis
, dis
;

int dijkstra(int s, int e){

for(int i = 0; i < n; i++) {
dis[i] = map[s][i];
vis[i] = 0;
}

dis[s] = 0;
vis[s] = 1;

for(int i = 0; i < n; i++){
int x, m = INF;
for(int j = 0; j < n; j++){
if(!vis[j] && dis[j] <= m){
m = dis[j];
x = j;
}
}
vis[x] = 1;
for(int j = 0; j < n; j++){
if(!vis[j]){
dis[j] = min(dis[j], dis[x] + map[x][j]);
}
}
}
if(dis[e] == INF) return -1;
else return dis[e];
}
int main(){
while(~scanf("%d %d", &n, &m)){
for(int i = 0; i < n; i++){
for(int j = 0; j < n; j++){
map[i][j] = (i == j ? 0 : INF);
}
}
int u, v, w;
for(int i = 1; i <= m; i++){
scanf("%d %d %d", &u, &v, &w);
if(w < map[u][v]){
map[u][v] = map[v][u] = w;
}
}

int s = 0, e = 0;

scanf("%d %d", &s, &e);

int ans = dijkstra(s, e);

printf("%d\n", ans);

}
}
/*
3 3
0 1 1
0 2 3
1 2 1
0 2

3 1
0 1 1
1 2
*/