输入的第一行为两个整数 nn 和 mm(1 < n \leq 1001<n≤100,1 \leq m \leq 2001≤m≤200),代表图中的顶点数和边数。接下来的 mm 行,每行输入两个整数 xx(0 \leq x \leq n-10≤x≤n−1) 和 yy(0 \leq y \leq n-10≤y≤n−1),表示一条从 xx 连向 yy 的无向边。之后输入一个整数 kk(0 \leq k < n0≤k<n),表示深度优先搜索的起点。
输出深度优先搜索的遍历结果,每个元素各占一行。
#include <stdio.h> #include <stdlib.h> #include <string.h> #define MAX_N 10000 typedef struct Node { int vertex; struct Node *next; } Node, *LinkedList; LinkedList insert_node(LinkedList head, int index) { Node *node = (Node *)malloc(sizeof(Node)); node->vertex = index; node->next = head; head = node; return head; } typedef struct Graph { LinkedList edges[MAX_N]; int n; int visited[MAX_N]; } Graph; void init(Graph * g, int n) { g->n = n; for (int i = 0; i < g->n; ++i) { g->edges[i] = NULL; } memset(g->visited,0,sizeof(g->visited)); } void insert(Graph *g, int x, int y) { if (x < 0 || x >= g->n || y < 0 || y >= g->n) { return ; } g->edges[x] = insert_node(g->edges[x], y); g->edges[y] = insert_node(g->edges[y], x); } void clear(Graph *g) { for (int i = 0; i < g->n; ++i) { Node *head = g->edges[i]; while (head != NULL) { Node *delete_node = head; head = head->next; free(delete_node); } } free(g); } void dfs(Graph *g, int index) { printf("%d\n",index); g->visited[index]=1; for(Node *adj=g->edges[index];adj!=NULL;adj=adj->next) { if(g->visited[adj->vertex]!=1) { dfs(g,adj->vertex); } } } int main() { int n, m, k; scanf("%d %d", &n, &m); Graph *graph = (Graph *)malloc(sizeof(Graph)); init(graph, n); for (int i = 0; i < m; ++i) { int x, y; scanf("%d %d", &x, &y); insert(graph, x, y); } scanf("%d", &k); dfs(graph, k); clear(graph); return 0; }