用c语言邻接表创建图

邻接表是一种表示图的数据结构，它由一个数组和一个链表组成。数组中的每个元素表示一个顶点，链表中的每个节点表示该顶点的邻居。下面是用C语言实现邻接表创建图的步骤：

1. 定义邻接表节点结构体

struct AdjListNode {
    int dest;
    struct AdjListNode* next;
};

2. 定义邻接表结构体

struct AdjList {
    struct AdjListNode* head;
};

3. 定义图结构体

struct Graph {
    int V;
    struct AdjList* array;
};

4. 创建邻接表节点

struct AdjListNode* newAdjListNode(int dest) {
    struct AdjListNode* newNode = (struct AdjListNode*)malloc(sizeof(struct AdjListNode));
    newNode->dest = dest;
    newNode->next = NULL;
    return newNode;
}

5. 创建图

struct Graph* createGraph(int V) {
    struct Graph* graph = (struct Graph*)malloc(sizeof(struct Graph));
    graph->V = V;
    graph->array = (struct AdjList*)malloc(V * sizeof(struct AdjList));
    int i;
    for (i = 0; i < V; ++i) {
        graph->array[i].head = NULL;
    }
    return graph;
}

6. 添加边

void addEdge(struct Graph* graph, int src, int dest) {
    struct AdjListNode* newNode = newAdjListNode(dest);
    newNode->next = graph->array[src].head;
    graph->array[src].head = newNode;
    newNode = newAdjListNode(src);
    newNode->next = graph->array[dest].head;
    graph->array[dest].head = newNode;
}

7. 示例代码

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

struct AdjListNode {
    int dest;
    struct AdjListNode* next;
};

struct AdjList {
    struct AdjListNode* head;
};

struct Graph {
    int V;
    struct AdjList* array;
};

struct AdjListNode* newAdjListNode(int dest) {
    struct AdjListNode* newNode = (struct AdjListNode*)malloc(sizeof(struct AdjListNode));
    newNode->dest = dest;
    newNode->next = NULL;
    return newNode;
}

struct Graph* createGraph(int V) {
    struct Graph* graph = (struct Graph*)malloc(sizeof(struct Graph));
    graph->V = V;
    graph->array = (struct AdjList*)malloc(V * sizeof(struct AdjList));
    int i;
    for (i = 0; i < V; ++i) {
        graph->array[i].head = NULL;
    }
    return graph;
}

void addEdge(struct Graph* graph, int src, int dest) {
    struct AdjListNode* newNode = newAdjListNode(dest);
    newNode->next = graph->array[src].head;
    graph->array[src].head = newNode;
    newNode = newAdjListNode(src);
    newNode->next = graph->array[dest].head;
    graph->array[dest].head = newNode;
}

void printGraph(struct Graph* graph) {
    int v;
    for (v = 0; v < graph->V; ++v) {
        struct AdjListNode* pCrawl = graph->array[v].head;
        printf("\n Adjacency list of vertex %d\n head ", v);
        while (pCrawl) {
            printf("-> %d", pCrawl->dest);
            pCrawl = pCrawl->next;
        }
        printf("\n");
    }
}

int main() {
    int V = 5;
    struct Graph* graph = createGraph(V);
    addEdge(graph, 0, 1);
    addEdge(graph, 0, 4);
    addEdge(graph, 1, 2);
    addEdge(graph, 1, 3);
    addEdge(graph, 1, 4);
    addEdge(graph, 2, 3);
    addEdge(graph, 3, 4);
    printGraph(graph);
    return 0;
}