题目链接：http://acm.hdu.edu.cn/showproblem.php?pid=2680
题目意思：实质就是给定一个多源点到单一终点的最短路。
卑鄙题～～～有向图。初始化map时 千万不要写成 map[i][j] = map[j][i] = X。
1 #include <iostream>
2 #include <cstdio>
3 #include <cstdlib>
4 #include <cstring>
5 using namespace std;
6
7 #define INF 0xfffffff
8 const int maxn = 1000 + 5;
9 int dist[maxn], map[maxn][maxn], vis[maxn];
10 int n, m, s;
11
12 void Init()
13 {
14 for (int i = 0; i <= n; i++)
15 {
16 for (int j = 0; j <= n; j++)
17 map[i][j] = (i == j ? 0 : INF);
18 }
19 int p, q, t, w;
20 for (int i = 0; i < m; i++)
21 {
22 scanf("%d%d%d", &p, &q, &t);
23 if (map[p][q] > t)
24 map[p][q] = t; // 写成map[p][q] = map[q][p] = t 会wa的！！！
25 }
26 scanf("%d", &w);
27 for (int i = 0; i < w; i++)
28 {
29 scanf("%d", &p);
30 map[0][p] = map[p][0] = 0;
31 }
32 for (int i = 0; i <= n; i++)
33 dist[i] = map[0][i];
34 }
35
36 void Dijkstra()
37 {
38 int u, maxx;
39 memset(vis, 0, sizeof(vis));
40 for (int i = 0; i <= n; i++)
41 {
42 maxx = INF;
43 for (int j = 0; j <= n; j++)
44 {
45 if (!vis[j] && dist[j] < maxx)
46 maxx = dist[u=j];
47 }
48 vis[u] = 1;
49 for (int j = 0; j <= n; j++)
50 {
51 if (dist[j] > dist[u] + map[u][j])
52 dist[j] = dist[u] + map[u][j];
53 }
54 }
55 }
56
57 int main()
58 {
59 while (scanf("%d%d%d", &n, &m, &s) != EOF)
60 {
61 Init();
62 Dijkstra();
63 printf("%d\n", dist[s] == INF ? -1 : dist[s]);
64 }
65 return 0;
66 }
hdu 2680 Choose the best route 解题报告
时间： 2024-08-26 20:41:29