127 lines
2.8 KiB
Plaintext
127 lines
2.8 KiB
Plaintext
/* file name: dfs.c */
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/* 圖形的追蹤: 相鄰串列與蹤向優先搜尋法(DFS)*/
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#include <stdio.h>
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#include <stdlib.h>
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#define MAX_V 100 /*最大節點數*/
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#define TRUE 1
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#define FALSE 0
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/*定義資料結構*/
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typedef struct node_tag {
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int vertex;
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struct node_tag *link;
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} Node;
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Node *adjlist[MAX_V+1]; /*宣告相鄰串列*/
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int visited[MAX_V+1]; /*記錄頂點是否已拜訪*/
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int total_vertex;
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void build_adjlist(void);
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void show_adjlist(void);
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void dfs(int);
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Node *searchlast(Node *);
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int main()
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{
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build_adjlist(); /*以相鄰串列表示圖形*/
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show_adjlist(); /*顯示串列之資料*/
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puts("\n------Depth Fisrt Search------");
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dfs(1); /*圖形之蹤向優先搜尋，以頂點1為啟始頂點*/
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printf("\n");
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return 0;
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}
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void build_adjlist()
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{
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FILE *fptr;
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Node *node,*lastnode;
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int vi,vj ,weight;
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fptr = fopen("dfs.dat", "r");
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if (fptr == NULL) {
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perror("dfs.dat");
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exit(0);
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}
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/* 讀取節點總數 */
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fscanf(fptr, "%d", &total_vertex);
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for (vi = 1; vi <= total_vertex; vi++) {
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/*設定陣列及各串列啟始值*/
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visited[vi] = FALSE;
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adjlist[vi] = (Node *)malloc(sizeof(Node));
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adjlist[vi]->vertex = vi;
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adjlist[vi]->link = NULL;
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}
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/* 讀取節點資料 */
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for (vi = 1; vi <= total_vertex; vi++)
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for (vj = 1; vj <= total_vertex; vj++) {
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fscanf(fptr,"%d",&weight);
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/* 資料檔以相鄰矩陣格式儲存,以1代表相鄰
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0 代表不相鄰，將相鄰頂點鏈結在各串列後 */
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if (weight != 0) {
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node = (Node *)malloc(sizeof(Node));
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node->vertex = vj;
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node->link = NULL;
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lastnode = searchlast(adjlist[vi]);
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lastnode->link = node;
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}
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}
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fclose(fptr);
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}
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/*顯示各相鄰串列之資料*/
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void show_adjlist()
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{
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int index;
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Node *ptr;
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puts("Head adjacency nodes");
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puts("------------------------------");
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for (index = 1; index <= total_vertex; index++) {
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printf("V%-2d ",adjlist[index]->vertex);
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ptr = adjlist[index]->link;
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while (ptr != NULL) {
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printf("--> V%d ",ptr->vertex);
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ptr = ptr->link;
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}
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printf("\n");
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}
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}
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/*圖形之蹤向優先搜尋*/
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void dfs(int v)
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{
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Node *ptr;
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int w;
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printf("V%d ",adjlist[v]->vertex);
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visited[v] = TRUE; /*設定v頂點為已拜訪過*/
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ptr = adjlist[v]->link; /*拜訪相鄰頂點*/
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do {
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/* 若頂點尚未走訪，則以此頂點為新啟始點繼續
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做蹤向優先搜尋法走訪，否則找與其相鄰的頂點
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直到所有相連接的節點都已走訪 */
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w = ptr->vertex;
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if (!visited[w])
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dfs(w);
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else
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ptr = ptr->link;
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} while (ptr != NULL);
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}
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/*搜尋串列最後節點函數*/
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Node *searchlast( Node *linklist )
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{
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Node *ptr;
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ptr = linklist;
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while (ptr->link != NULL)
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ptr = ptr->link;
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return ptr;
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}
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