数据结构之邻接表存储图

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用邻接表存图适合稀疏图，不会浪费太多空间。写的时候一定要思路清晰，点和边的结构体存储要明确他们都包含什么内容。

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#include <bits/stdc++.h>
using namespace std;
typedef struct Arcnode{
    int vertex,data;                //这条边的终点 以及权值
    struct Arcnode *nextArc;              //与这条边同起点的下一条边
}Arcnode;
typedef struct vernode{
    int data;                   //顶点数据
     Arcnode *nextArc;            // 以该点为起点的边
}vernode;
typedef struct {
    vernode vertex[1001];
    int vernum,arcnum;
}Graph;
int locate(Graph G, int x)
{
    for(int i = 1 ; i <= G.vernum; ++i)
    {
        if(G.vertex[i].data == x)
        {
            return i;
        }
    }
}
void create(Graph &G)
{
    int a,b,w;
    cin >> G.vernum >> G.arcnum;
    for(int i = 1; i <= G.vernum ; ++i)
    {
        cin >> G.vertex[i].data;
        G.vertex[i].nextArc = NULL;
    }
    for(int i = 1; i <= G.arcnum; ++i)
    {
        cin >> a >> b >> w;
        int A = locate(G,a);
        int B = locate(G,b);
        Arcnode *p,*p1;
        p = new Arcnode;             //！！！这一步总是忘记
        p -> vertex = B;
        p -> nextArc = G.vertex[A].nextArc;
        p -> data = w;
        G.vertex[A].nextArc = p;
        p = new Arcnode;
        p -> vertex = A;
        p -> nextArc = G.vertex[B].nextArc;
        p -> data = w;
        G.vertex[B].nextArc = p;
    }
}
int main()
{
    Graph G;
    create(G);
    Arcnode *p;
    for(int i = 1; i <= G.vernum; ++i){
    p = G.vertex[i].nextArc;
    while(p != NULL)
    {
        cout << p -> data << ' ' << p -> vertex << '\n';
        p = p -> nextArc;
    }
    cout << '\n';
    }
}