无向图以邻接表存储，试编写图的基本运算（输入两顶点序号插入边、输入两顶点序号查找是否存在边）。用c语言实现

在无向图的邻接表存储中，我们通常会为每个顶点维护一个链表，链表中的节点表示与该顶点相连的其他顶点。以下是使用C语言实现无向图的一些基本操作：

1. 结构体定义：

#include <stdio.h>
#include <stdlib.h>

typedef struct Node {
    int vertex;
    struct Node* next;
} Edge;

typedef struct Graph {
    int vertices; // 顶点数
    Edge** adj;   // 邻接表数组
} Graph;

2. 初始化和删除函数：

void createGraph(Graph* graph, int vertices) {
    graph->vertices = vertices;
    graph->adj = (Edge**)malloc(sizeof(Edge*) * vertices);
    for (int i = 0; i < vertices; ++i) {
        graph->adj[i] = NULL;
    }
}

void deleteGraph(Graph* graph) {
    for (int i = 0; i < graph->vertices; ++i) {
        if (graph->adj[i]) {
            free(graph->adj[i]);
        }
    }
    free(graph->adj);
}

3. 插入边函数（假设两个顶点已存在）：

void addEdge(Graph* graph, int src, int dest) {
    Edge* newNode = (Edge*)malloc(sizeof(Edge));
    newNode->vertex = dest;
    newNode->next = graph->adj[src];
    graph->adj[src] = newNode;

    // 如果dest还没有从src指向，则添加反向链接
    if (graph->adj[dest] == NULL) {
        newNode = (Edge*)malloc(sizeof(Edge));
        newNode->vertex = src;
        newNode->next = graph->adj[dest];
        graph->adj[dest] = newNode;
    }
}

4. 检查边是否存在：

int isAdjacent(Graph* graph, int src, int dest) {
    Edge* current = graph->adj[src];
    while (current != NULL) {
        if (current->vertex == dest) {
            return 1; // 存在边
        }
        current = current->next;
    }
    return 0; // 不存在边
}