拓扑排序之邻接表实验

拓扑排序之邻接表实验

标签：拓扑排序

方法一：
FindInDegree()函数对各个顶点求入度，保存在indegree[]数组中。

#include <stdio.h>
#include <stdlib.h>
#include <stack>
using namespace std;

#define M 20
typedef char vertextype;
int indegree[M];

typedef struct node{
    int adjvex;
    struct node *next;
}edgenode;

typedef struct de{
    edgenode  *FirstEdge;
    vertextype vertex;
}vertexnode;

typedef struct{
    vertexnode adjlist[M];
    int n,e;
}AovGraph;

void  creat(AovGraph *g, char *filename){
    int i, j, k;
    edgenode *s;
    FILE *fp;

    fp = fopen(filename, "r");
    if(fp){
        fscanf(fp, "%d %d", &g->n, &g->e);
        for(i = 0; i < g->n; i++){
            fscanf(fp, "%1s", &g->adjlist[i].vertex);
            g->adjlist[i].FirstEdge = NULL;
        }
        for(k = 0; k < g->e; k++){
            s = (edgenode*)malloc(sizeof(edgenode));

            fscanf(fp, "%d %d", &i, &j);
            s->adjvex = j;
            s->next = g->adjlist[i].FirstEdge;
            g->adjlist[i].FirstEdge = s;
        }
    }
}

void FindInDegree(AovGraph g, int indegree[M]){
    for(int i = 0; i < g.n; i++){
        int total = 0;

        for(int j = 0; j < g.n; j++){
            edgenode *p = g.adjlist[j].FirstEdge;

            while(p){
                if((p->adjvex + '0') == g.adjlist[i].vertex)  total++;  ///'0'
                p = p->next;
            }
        }
        indegree[i] = total;
    }
}

void print(AovGraph g){
    int i;

    FindInDegree(g, indegree);
    for(i = 0; i < g.n; i++){
        printf("indegree(%d) %c",  indegree[i], g.adjlist[i].vertex);
        edgenode *p = g.adjlist[i].FirstEdge;
        while(p){
            printf("-->%d", p->adjvex);
            p = p->next;
        }
        printf("\n");
    }
}

void Tsort(AovGraph g){
    stack <int> S;
    int i, k;

    FindInDegree(g, indegree);
    for(i = 0; i < g.n; i++)
        if(!indegree[i])  S.push(g.adjlist[i].vertex - '0');  ///
    int countv = 0;

    while(!S.empty()){
        i = S.top(), S.pop();
        printf("%c", g.adjlist[i].vertex);
        ++countv;
        for(edgenode *p = g.adjlist[i].FirstEdge; p; p = p->next){
            k = p->adjvex;
            if(!(--indegree[k]))  S.push(k);
        }
    }
    if(countv < g.n)  printf("failed\n");
}

int main(){
    AovGraph g;

    creat(&g, "topo.txt");
    print(g), printf("\n");
    Tsort(g), printf("\n");

    return 0;
}

方法二：
在邻接表头结点中增加一个存放顶点入度的域，在读图的同时计算各顶点的入度。

#include <stdio.h>
#include <stdlib.h>
#include <stack>
using namespace std;

#define M 20
typedef char vertextype;

typedef struct node{
    int adjvex;
    struct node *next;
}edgenode;

typedef struct de{
    edgenode  *FirstEdge;
    vertextype vertex;
    int id;  //顶点的入度
}vertexnode;

typedef struct{
    vertexnode adjlist[M];
    int n,e;
}AovGraph;

void  creat(AovGraph *g, char *filename){
    int i, j, k;
    edgenode *s;
    FILE *fp;

    fp = fopen(filename, "r");
    if(fp){
        fscanf(fp, "%d %d", &g->n, &g->e);
        for(i = 0; i < g->n; i++){
            fscanf(fp, "%1s", &g->adjlist[i].vertex);
            g->adjlist[i].FirstEdge = NULL;
            g->adjlist[i].id = 0;  //入度初始化为0
        }
        for(k = 0; k < g->e; k++){
            s = (edgenode*)malloc(sizeof(edgenode));
            fscanf(fp, "%d %d", &i, &j);
            s->adjvex = j;
            g->adjlist[j].id++;  //顶点j的入度加1
            s->next = g->adjlist[i].FirstEdge;
            g->adjlist[i].FirstEdge = s;
        }
    }
}

void print(AovGraph g){
    int i;

    for(i = 0; i < g.n; i++){
        printf("indegree(%d) %c",  g.adjlist[i].id, g.adjlist[i].vertex);
        edgenode *p = g.adjlist[i].FirstEdge;
        while(p){
            printf("-->%d", p->adjvex);
            p = p->next;
        }
        printf("\n");
    }
}

void Tsort(AovGraph g){
    stack <int> S;
    int i, k;

    for(i = 0; i < g.n; i++)
        if(!g.adjlist[i].id)  S.push(g.adjlist[i].vertex - '0');  ///
    int countv = 0;

    while(!S.empty()){
        i = S.top(), S.pop();
        printf("%c", g.adjlist[i].vertex);
        ++countv;
        for(edgenode *p = g.adjlist[i].FirstEdge; p; p = p->next){
            k = p->adjvex;
            if(!(--g.adjlist[k].id))  S.push(k);
        }
    }
    if(countv < g.n)  printf("failed\n");
}

int main(){
    AovGraph g;

    creat(&g, "topo.txt");
    print(g), printf("\n");
    Tsort(g), printf("\n");

    return 0;
}

数据文件：

实验结果：