这段代码是我根据算法设计手册构建的代码,但我无法编译它,因为我对指针缺乏经验,我认为这是我无法编译它的主要原因:
如果有人可以在 djikstra 中进行一些更改,使其能够使用当前配置通过堆。
#include<iostream>
#include<stdio.h>
#include<stdlib.h>
using namespace std;
const int MAXV=1000;
const int MAXINT=99999;
typedef struct{
int y;
int weight;
struct edgenode *next;
}edgenode;
typedef struct{
edgenode *edges[MAXV+1];
int degree[MAXV+1];
int nvertices;
int nedges;
bool directed;
}graph;
void add_edge(graph *g,int x,int y,int weight,bool directed);
void read_graph(graph *g,bool directed){
int x,y,weight,m;
g->nvertices=0;
g->nedges=0;
g->directed=directed;
for(int i=1;i<MAXV;++i) g->degree[i]=0;
for(int i=1;i<MAXV;++i) g->edges[i]=NULL;
scanf("%d %d",&(g->nvertices),&m);
for(int i=1;i<=m;++i){
scanf("%d %d %d",&x,&y,&weight);
add_edge(g,x,y,weight,directed);
}
}
void add_edge(graph *g,int x,int y,int weight,bool directed){
edgenode *p;
p=malloc(sizeof(edgenode));
p->weight=weight;
p->y=y;
p->next=g->edges[x];
g->edges[x]=p;
g->degree[x]++;
if(directed==false) add_edge(g,y,x,weight,true);
else g->nedges++;
}
int dijkstra(graph *g,int start,int end){
edgenode *p;
bool intree[MAXV+1];
int distance[MAXV+1];
for(int i=1;i<=g->nvertices;++i){
intree[i]=false;
distance[i]=MAXINT;
}
distance[start]=0;
int v=start;
while(intree[v]==false){
intree[v]=true;
p=g->edges[v];
while(p!=NULL){
int cand=p->y;
int weight=p->weight;
if(distance[cand] > distance[v]+weight) distance[cand]=distance[v]+weight;
p=p->next;
}
v=1;
int dist=MAXINT;
for(int i=1;i<=g->nvertices;++i)
if((intree[i]==false) && (dist > distance[i])){
dist=distance[i];
v=i;
}
}
return distance[end];
}
int main(){
graph g;
read_graph(&g,false);
int x=1,y,shortest;
while(x!=0){
scanf("%d %d",&x,&y);
shortest=dijkstra(&g,x,y);
printf("The shortest path from %d to %d is %d",x,y,shortest);
}
return 0;
}
最佳答案
更改结构体的定义,它就会编译。
struct edgenode_tag
{
int y;
int weight;
struct edgenode_tag *next;
};
typedef edgenode_tag edgenode;
虽然这可以解决您的问题,但在比我更好的人发表评论之前,请不要相信我的回答。
您的代码出了什么问题?
在编译器知道该类型之前,您正在使用 typedef-ed type。相反,您需要使用structural_tag来定义类型本身的成员指针。
typedef struct
{
...
my_struct* pS;
...
} my_struct; // at this point compiler will know about *my_struct* type
// Hence, you can not use that name until after this line.
// To define the member pointer of type itself you need to
// to use the struct_tag, as I did in your example.
// where, struct_tag is *edgenode_tag*
编辑:
此外,malloc 返回 *void**,您需要将其转换为要分配给它的类型。 因此,在函数 add_edges 内部,进行此更正(请在书中阅读更多相关内容,理解这一点很重要):
p = (edgenode*)malloc(sizeof(edgenode));
关于c++ - 我无法编译此 dijkstra 代码。 (算法设计手册),我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/3136625/