hihoCoder#1081 最短路径·一

原题地址

Dijkstra算法，甚至都不用优化（堆或优先队列）即可过

代码：

 1 #include <iostream>
 2 #include <vector>
 3 #include <set>
 4 #include <cstring>
 5
 6 using namespace std;
 7
 8 #define MAX_POINT 1024
 9 #define MAX_EDGE 16384
10
11 int N, M, S, T;
12 int graph[MAX_POINT][MAX_POINT];
13 int v[MAX_POINT];
14
15 void bfs() {
16   v[S] = 1;
17   while (true) {
18     int k = 0;
19     for (int i = 1; i <= N; i++) {
20       if (!v[i] && graph[S][i] < graph[S][k])
21         k = i;
22     }
23     if (k == T)
24       break;
25     v[k] = 1;
26     for (int i = 1; i <= N; i++)
27       if (!v[i] && graph[S][i] > graph[S][k] + graph[k][i])
28         graph[S][i] = graph[S][k] + graph[k][i];
29   }
30 }
31
32 int main() {
33   memset(v, 0, sizeof(v));
34   memset(graph, 64, sizeof(graph));
35
36   scanf("%d%d%d%d", &N, &M, &S, &T);
37   for (int i = 0; i < M; i++) {
38     int u, v, len;
39     scanf("%d%d%d", &u, &v, &len);
40     graph[u][v] = graph[v][u] = min(graph[u][v], len);
41   }
42
43   bfs();
44
45   printf("%d\n", graph[S][T]);
46 }