[英]Finding path between nodes using BFS in C language
I'm new to C language and it's been harder for me to work with pointers after working in Java😥 I was trying to write a code of finding a path (not necessary minimum) between two nodes in a graph using breadth-first-search. 我是C语言的新手,在Java中工作后,使用指针变得更加困难😥我试图编写代码以使用广度优先搜索在图中的两个节点之间查找路径(不必要的最小值) 。 Here is my code :
这是我的代码:
#include<stdio.h>
#include<stdlib.h>
#define MAXSIZE 200
void push(int a);
int pop(void);
void bfs(int a,int b,int len);
int nextnode(int a);
typedef struct node{
int data;
struct node* next;
}node;
int res[MAXSIZE];
int visited[MAXSIZE];
int rear,front;
node* graph[MAXSIZE];
int len;
int path[MAXSIZE];
int nextnode(int a)
{
if(graph[a]==NULL)
return -1;
else
{
struct node* c=graph[a];
while(visited[c->data]!=1 && c!=NULL)
{
c=c->next;
}
if(c==NULL)
return -1;
else
return c->data;
}
}
void push(int a)
{
path[rear]=a;
rear++;
}
int pop()
{
if(front==rear)
return -1;
int num=path[front];
front++;
return num;
}
int main()
{
rear=0;
len=0;
front=0;
int n,e;
int i,a,b;
printf("%s\n%s", "Inputting Graph... ","Enter number of nodes and edges: ");
scanf("%d %d",&n,&e);
printf("%s %d %s\n", "Graph Created with",n,"nodes without any edge.");
printf("%s\n","Enter the edges in 1 2 format if an edge exist from Node 1 to Node 2" );
for(i=1;i<=n;i++)
{
graph[i]=NULL;
visited[i]=0;
}
struct node* new = (struct node*)malloc(sizeof(struct node));
for(i=0;i<e;i++)
{
scanf("%d %d",&a,&b);
new->data=b;
new->next=NULL;
struct node* curr=graph[a];
if(curr==NULL)
{
graph[a]=new;
}
else
{
while(curr->next!=NULL)
{
curr=curr->next;
}
curr->next=new;
}
}
printf("%s\n", "Graph Created Successfully.");
printf("%s", "Enter the node numbers between which the path is to be found between: ");
scanf("%d %d",&a,&b);
bfs(a,b,0);
printf("Length is %d\n",len);
for(i=1;i<=len;i++)
{
printf("%d\n",res[len]);
}
}
void bfs(int a,int b,int len)
{
int c;
visited[a]=1;
int flag=0;
while(a!=-1)
{
c=nextnode(a);
while(c!=-1)
{
c=nextnode(a);
if(c==b)
{
flag=1;
break;
}
push(c);
visited[c]=1;
}
len++;
res[len]=a;
if(flag==1)
{
res[len]=b;
break;
}
a=pop();
}
}
I know it's huge, but please mind going through it once. 我知道它很大,但是请介意一次。 The problem I'm getting is Segmentation Fault after I input all the values, and before dfs() function call!
输入所有值之后,并且在dfs()函数调用之前,我遇到的问题是分段错误! Please Help.
请帮忙。
For understanding: I have used array of Lists. 为了理解:我使用了List数组。 Each array index denotes a node and the list denotes all the edges it is connected to.
每个数组索引表示一个节点,列表表示其连接到的所有边。 eg: if my Graph has 1->2, 1->3, 2-3 edges;
例如:如果我的图表具有1-> 2、1-> 3、2-3个边; graph[1] will have a list 2->3->NULL.
graph [1]将具有列表2-> 3-> NULL。 And graph[2] will have 3->NULL.
并且graph [2]将具有3-> NULL。
Thank you. 谢谢。
EDIT As pointed out by Aditi, the error was in the line where nextnode function ran the while loop. 编辑正如Aditi指出的那样,该错误发生在nextnode函数运行while循环的那一行中。 After changing the code to
将代码更改为
while(c != NULL && visited[c->data] == 1 )
the program ran flawlessly. 该程序运行完美。 Thanks!
谢谢!
我认为您要执行的操作不是graph [i] = NULL,而是graph [i]-> next = NULL
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