单源最短路径 : Dijkstra 算法

来源：互联网发布：历年固定资产投资数据编辑：程序博客网时间：2024/04/28 23:45

public class Dijkstra {static final int M = 10000;static void dijkstra(int[][] edges, int s) {int vertexs = edges.length;// distint[] d = new int[vertexs];// πint[] p = new int[vertexs];boolean[] visited = new boolean[vertexs];for(int i = 0; i < vertexs; i++) {d[i] = M;p[i] = -1;}d[s] = 0;for(int cnt = 0; cnt < vertexs; cnt++) {int u = -1;//extract-minint min = Integer.MAX_VALUE;for(int i = 0; i < vertexs; i++) {if(!visited[i] && d[i] < min) {min = d[i];u = i;}}//unionvisited[u] = true;//relaxationfor(int v = 0; v < edges[u].length; v++) {if(d[v] > (d[u] + edges[u][v])) {d[v] = d[u] + edges[u][v];p[v] = u;}}}//printfor(int i = 0; i < vertexs; i++) {char u = (char)('A' + s);char v = (char)('A' + i);if (d[i] < M) {System.out.printf("%c -> %c (%d) : ", u, v, d[i]);StringBuilder sb = new StringBuilder();int j = i;if(s != i)sb.append(v);while (p[j] != -1) {sb.insert(0, (char) ('A' + p[j]) + " - ");j = p[j];}System.out.println(sb.toString());} else {System.out.printf("%c -> %c (∞) : \n", u, v);}}}public static void main(String[] args) {int[][] edges = {{0,M,M,M, M, M, 9},{20, 0, 10,30, M, M, M},{M, M, 0, M, 5, M, 18},{M, M, M, 0, M, M, M},{M, M, M, 12, 0, M, 15},{M, M, M, M, 8, 0, 10},{M, M, 18, M, M, M, 0}};dijkstra(edges, 1);}}

输出结果：

B -> A (20) : B - A
B -> B (0) :
B -> C (10) : B - C
B -> D (27) : B - C - E - D
B -> E (15) : B - C - E
B -> F (∞) :
B -> G (28) : B - C - G