我正在尝试修改我的Prim算法实现,以便跟踪源节点到其他节点的距离。由于Prim算法和Dijkstra算法几乎相同,所以我无法确定自己哪里出了问题。
我知道问题出在哪里,但是无法解决。
下面是我的代码,请问如何修改它以打印源节点到所有其他节点的最短距离。最短距离存储在名为dist[]的数组中。
代码:
package Graphs;
import java.util.ArrayList;
public class Prims {
static int no_of_vertices = 0;
public static void main(String[] args) {
int[][] graph = {{0, 2, 0, 6, 0},
{2, 0, 3, 8, 5},
{0, 3, 0, 0, 7},
{6, 8, 0, 0, 9},
{0, 5, 7, 9, 0},
};
no_of_vertices = graph.length;
int [][] result = new int [no_of_vertices][no_of_vertices];
boolean[] visited = new boolean[no_of_vertices];
int dist[] = new int[no_of_vertices];
for (int i = 0; i < no_of_vertices; i++)
for (int j = 0; j < no_of_vertices; j++) {
result[i][j]= 0;
if (graph[i][j] == 0) {
graph[i][j] = Integer.MAX_VALUE;
}
}
for (int i = 0; i < no_of_vertices; i++) {
visited[i] = false;
dist[i] = 0;
}
ArrayList<String> arr = new ArrayList<String>();
int min;
visited[0] = true;
int counter = 0;
while (counter < no_of_vertices - 1) {
min = 999;
for (int i = 0; i < no_of_vertices; i++) {
if (visited[i] == true) {
for (int j = 0; j < no_of_vertices; j++) {
if (!visited[j] && min > graph[i][j]) {
min = graph[i][j];
dist[i] += min; // <------ Problem here
visited[j] = true;
arr.add("Src :" + i + " Destination : " + j
+ " Weight : " + min);
}
}
}
}
counter++;
}
for (int i = 0; i < no_of_vertices; i++) {
System.out.println("Source : 0" + " Destination : " + i
+ " distance : " + dist[i]);
}
for (String str : arr) {
System.out.println(str);
}
}
}
在计算距离数组时存在错误,因为它忘记了将源节点到目标节点的任何中间节点的距离加入其中。