图的深度优先遍历算法

图的深度优先遍历算法，适用无向图和有向图

跟树的先序遍历实现思想相同，只不过多了个数组标记已访问的顶点


#include <stdio.h>

#include <iostream>
#include <stdlib.h>
#include <time.h>

using namespace std;


#define MAX_NUM 20                   //顶点的最大个数

bool visited[5];               //设置全局数组，记录标记顶点是否被访问过
int global_counter = 10;
typedef struct {
    int Vex[MAX_NUM];
    int Edge[MAX_NUM][MAX_NUM];
    int vexnum;
}Graph;


int FirstNeighbor(Graph g, int x){
    for (int i = 1; i<=g.vexnum; i++) {
        if (g.Edge[x][i]>0) {
            return g.Vex[i];
        }
    }
    return -1;
}
// 优化
int NextNeighbor(Graph g, int x, int y){
    for (int i = y+1; i<=g.vexnum; i++) {
        if (g.Edge[x][i]>0) {
            return g.Vex[i];
        }
    }
    return -1;
}
void DFS(Graph g, int v);
void DFSTraverse(Graph g){
    for (int i = 1; i<=g.vexnum; i++) {
        visited[i] = false;
    }
    for (int i = 1; i<=g.vexnum; i++) {
        if (!visited[i]) {
            cout << "分量" << endl;
            DFS(g, i);
        }
    }
}
void DFS(Graph g, int v){
    cout << "elements:" << v << endl;
    visited[v] = true;
    int w = 0;

    for (w = FirstNeighbor(g, v); w>=0; w = NextNeighbor(g, v, w)) {
        if (!visited[w]) {
            DFS(g, w);
        }
    }
}


int main(){
    std::cout << "welcome, to my world!" << std::endl;
    Graph graph;
    for (int i=1; i<=5; i++) {
        graph.Vex[i] = i;
    }
    for (int i=1; i<=5; i++) {
        for (int j = 1; j<=5; j++) {
            if (i==j) {
                graph.Edge[i][j] = 0;
            }else{
                graph.Edge[i][j] = 0;
            }
            
        }
    }
    graph.Edge[1][2] = 1;
    graph.Edge[1][3] = 1;
    graph.Edge[2][4] = 1;
    graph.Edge[2][5] = 1;
    graph.Edge[4][3] = 1;
    graph.vexnum = 5;

    cout << "size of:" << sizeof(graph) <<endl;
    DFSTraverse(graph);
    return 0;
}