dijkstra

洛谷模板题链接：https://www.luogu.org/problem/P3371

 

 1 #include <iostream>
 2 #include <vector>
 3 #include <cstring>
 4 #include <cstdio>
 5 using namespace std;
 6 const int N   = 1e5 + 10;
 7 const int INF = 2147483647;
 8 
 9 //n = 顶点数; m = 边数; s = 起点 
10 int n, m, s;
11 
12 //第一个数是距离，第二个数为顶点 
13 vector<pair<int,int> > g[N];
14 int dist[N];
15 bool vis[N];
16 
17 void dijkstra(int s)
18 {
19     memset(vis, 0, sizeof(vis));
20     for(int i = 1; i <= n; i++)    dist[i] = INF;
21     dist[s] = 0;
22     while(1)
23     {    
24         int node = -1;
25         int minDist = INF;
26         
27         //在为标记的点中找到距离起点的最短距离 
28         for(int i = 1; i <= n; i++)
29         {
30             if(vis[i] == 0 && dist[i] < minDist)
31             {
32                 node = i;
33                 minDist = dist[i];
34             }
35         }
36         
37         if(node == -1)    break;
38         //标记该点 
39         vis[node] = 1;
40         
41         //更新 
42         for(int i = 0; i < g[node].size(); i++)
43         {
44             int v = g[node][i].second;
45             dist[v] = min(dist[v], dist[node] + g[node][i].first);
46         }
47             
48     }
49 }
50 
51 int main()
52 {
53     cin >> n >> m >> s; 
54     for(int i = 1; i <= m; i++)
55     {
56         int u, v, d;
57         scanf("%d %d %d", &u, &v, &d);
58         g[u].push_back(make_pair(d, v)); 
59     }
60     dijkstra(s);
61     for(int i = 1; i <= n; i++)    
62         i==1?cout<<dist[i]:cout<<" "<<dist[i];
63     return 0;
64 }

这是没有加优化的，数据加强的话，就会TLE。

posted @ 2019-10-18 22:28  nonameless  阅读(113)  评论(0)  编辑  收藏  举报