Question

我有一个图表，想要运行深度优先搜索，我想返回结果如：ABCDEFGHIJKLM，但我只得到了ABCDEHK。算法有什么问题？感谢

class Program
{
    static void Main(string[] args)
    {
        //create graph, adjacent matrix
        Graph aGraph = new Graph();
        aGraph.AddVertex("A");
        aGraph.AddVertex("B");
        aGraph.AddVertex("C");
        aGraph.AddVertex("D");
        aGraph.AddVertex("E");
        aGraph.AddVertex("F");
        aGraph.AddVertex("G");
        aGraph.AddVertex("H");
        aGraph.AddVertex("I");
        aGraph.AddVertex("J");
        aGraph.AddVertex("K");
        aGraph.AddVertex("L");
        aGraph.AddVertex("M");

        aGraph.AddEdge(0,1);
        aGraph.AddEdge(1,2);
        aGraph.AddEdge(2,3);
        aGraph.AddEdge(0,4);
        aGraph.AddEdge(4,5);
        aGraph.AddEdge(5,6);
        aGraph.AddEdge(0,7);
        aGraph.AddEdge(7,8);
        aGraph.AddEdge(8,9);
        aGraph.AddEdge(0,10);
        aGraph.AddEdge(10,11);
        aGraph.AddEdge(11,12);
    }
}

//vertex class
public class Vertex {
    public bool wasVisited;
    public string label;

    public Vertex(string label) {
        this.label = label;
        wasVisited = false;
    }
}

//Graph class
public class Graph {
    private const int NUM_VERTICES = 20;
    private Vertex[] vertices;
    private int[,] adjMatrix;
    int numVerts;
    private Stack gStack;

    public Graph() { 
        vertices = new Vertex[NUM_VERTICES];
        adjMatrix = new int[NUM_VERTICES,NUM_VERTICES];
        numVerts = 0;
        for (int j = 0; j <= NUM_VERTICES-1; j++)
            for (int k = 0; k < NUM_VERTICES - 1; k++)
                adjMatrix[j, k] = 0;
        gStack = new Stack();
    }

    public void AddVertex(string label)
    {
        vertices[numVerts] = new Vertex(label);
        numVerts++;
    }

    public void AddEdge(int start, int eend)
    {
        adjMatrix[start, eend] = 1;
        adjMatrix[eend, start] = 1;
    }

    public void ShowVertex(int v) {
        Console.Write(vertices[v].label+" ");
    }

    private int GetAdjUnvisitedVertex(int v) {
        for (int j = 0; j <= numVerts-1; j++)         //NUM_VERTICES or numVerts
            if ((adjMatrix[v, j] == 1) && (vertices[j].wasVisited == false))
                return j;
            return -1;
    }

    public void DepthFirstSearch()
    {
        vertices[0].wasVisited = true;
        ShowVertex(0);
        //Stack gStack = new Stack();
        gStack.Push(0);
        int v;
        while (gStack.Count > 0) {
            //v = GetAdjUnvisitedVertex(gStack.Peek());   
              v = GetAdjUnvisitedVertex(gStack.Count-1);
            if (v == -1)
                gStack.Pop();

            else {
                vertices[v].wasVisited = true;
                ShowVertex(v);
                gStack.Push(v);
            }           
        }
        for (int j = 0; j <= numVerts - 1; j++)     //NUM_VERTICES or numVerts
            vertices[j].wasVisited = false;            
    }

原始算法有这一行：

//v = GetAdjUnvisitedVertex(gStack.Peek());

但它与函数GetAdjUnvisitedVertex不匹配，所以我改为行：

v = GetAdjUnvisitedVertex(gStack.Count-1);

Answer 1

我浏览了你的代码，当我取消注释

时

//v = GetAdjUnvisitedVertex(gStack.Peek());

输出“A B C D E F G H I J K L M”也称为正确答案。当你有

v = GetAdjUnvisitedVertex(gStack.Count-1);

当您开始遍历图表中的第二条路径时（A - > E - > F - > G），您没有在正确的顶点上调用该函数。由于gStack在第二条路径下行时只有顶部顶点（A），因此调用GetAdjUnvisitedVertex（0）;它将返回下一个相邻的顶点H，并重复返回K。

如何从一个节点返回所有路径？

1 个答案: