DFS (Simple implementation based on C language)

DFS (Simple implementation based on C language)

General steps
(1) Put the initial state into the array and set it as the current state;
(2) Expand the current state, generate a new state and put it into the array, and set the newly generated state as the current state;
(3) Judge whether the current state is the same as the previous one. If it is repeated, return to the previous state and produce another state;
(4) Judge whether the current state is the target state, if it is the target, find a solution and end the algorithm.
(5) If the array is empty, there is no solution.
 

#include<stdio.h>
#include<stdlib.h>
#define MAX_VALUE 100
int visit[MAX_VALUE];
typedef struct ArcNode
{
	int adjvex;
	struct ArcNode*nextarc;
}ArcNode;
typedef struct VNode
{
	int data;
	ArcNode*firstarc;
}VNode,AdjList[MAX_VALUE];
typedef struct
{
	AdjList vertices;
	int vexnum, arcnum;
}ALGraph;
int LocateVex(ALGraph G, int v)
{
	for (int i = 0; i < G.vexnum; i++)
	{
		if (G.vertices[i].data == v)
		{
			return i;
		}
	}
}
void CreatUDG(ALGraph *G)
{
	ArcNode*p, *q;
	int i, j,v1, v2;
	printf("分别输入顶点个数和边的个数：\n");
	scanf("%d%d", &(G->vexnum), &(G->arcnum));
	printf("请输入各个顶点的值：\n");
	for (int i = 0; i < G->vexnum; i++)
	{
		scanf("%d", &(G->vertices[i].data));
		G->vertices[i].firstarc = NULL;
	}
	printf("分别输入各条边的两个顶点：\n");
	for (int k = 0; k < G->arcnum; k++)
	{
		scanf("%d%d", &v1, &v2);
		i = LocateVex(*G, v1);
		j = LocateVex(*G, v2);
		p = (ArcNode*)malloc(sizeof(ArcNode));
		p->adjvex = j;
		p->nextarc = NULL;
		p->nextarc = G->vertices[i].firstarc;
		G->vertices[i].firstarc = p;
		q = (ArcNode*)malloc(sizeof(ArcNode));
		q->adjvex = i;
		q->nextarc = NULL;
		q->nextarc = G->vertices[j].firstarc;
		G->vertices[j].firstarc = q;
	}
}
void PrintUDG(ALGraph G)
{
	ArcNode*p = NULL;
	for (int i = 0; i < G.vexnum; i++)
	{
		printf("第%d条边\n", i + 1);
		p = G.vertices[i].firstarc;
		while (p != NULL)
		{
			printf("%d  ", (p->adjvex)+1);
			p = p->nextarc;
		}
		printf("\n");
	}
}
void DFS(ALGraph G, int v)
{
	ArcNode*p;
	visit[v] = 1;
	printf("%d  ", G.vertices[v].data);
	p = G.vertices[v].firstarc;
	while (p != NULL)
	{
		if (!visit[p->adjvex] )
		{
			DFS(G, p->adjvex);
		}
		//当递归找到出口时 此时就会运行到下面的语句 即一个结点的遍历走到了头  
		//此时 再向后走  例如 第一条边的邻接表为 1 2 3  那么当2找到递归出口后
		//我们还要进行3的遍历  所以要有语句p=p->nextarc
		p = p->nextarc;
	}
}
void DFST(ALGraph G)//该函数用于不是连通图的时候 可以用for循环进行深度优先遍历
{
	for (int i = 0; i < G.vexnum; i++)
	{
		visit[i] = 0;
	}
	for (int i = 0; i < G.vexnum; i++)
	{
		if (!visit[i])
		{
			printf("\n第%d次调用\n", i);
			DFS(G, i);
		}
	}
}
int main()
{
	ALGraph G;
	CreatUDG(&G);
	PrintUDG(G);
	DFST(G);
	return 0;
}