edges.txt is used.it is the input adjacency list.
1 3
1 5
2 3
2 6
4 5
5 6
include<stdio.h>
include<stdlib.h>
include<conio.h>
int **adjL;
int v,*arr;
void dfs(int **adjL)
{
int j,i=0,temp,dfslabel=1,s=0,k=0,top=0;
int stack[v];
int *flag;
flag=(int*)calloc(v+1,sizeof(int));
for(i=0;i<=v;i++)
flag[i]=0;
stack[++top]=1;
flag[1]=3;
stack[top]=1;
while(1)
{
if(i==arr[stack[top]-1])
{
printf("examination of %d is complete",stack[top]);
top--;
}
if(top==-1)
break;
if(flag[adjL[stack[top]-1][i]]==0)
{
temp=adjL[stack[top]-1][i];
stack[top++]=temp;
i=0;
flag[temp]=stack[top-1];
printf("\nDFS label:%d ,current node=%d,linkprocessed %d to %d (tree edge)",dfslabel,stack[top-1],stack[top-1],temp);
dfslabel++;
}
else
{
if(flag[adjL[stack[top]-1][i]]==stack[top-1])
printf("\nbackedge");
else
printf("\ncycle");
i++;
}
}
}
int main()
{
FILE *fp;
int *index;
v=-1;
int num1,num2;
int i=0,j;
fp=fopen("edges.txt","r");
while(fscanf(fp,"%d %d",&num1,&num2)!=EOF)
{
if(num1>v)
v=num1;
if(num2>v)
v=num2;
}
printf("%d",v);
adjL=(int **)calloc(sizeof(int *),v);
arr=(int *)calloc(sizeof(int),v);
printf("\nHighest edge found = %d",v);
rewind(fp);
while(fscanf(fp,"%d %d",&num1,&num2)!=EOF)
{
arr[num1-1]++;
arr[num2-1]++;
}
rewind(fp);
for(i=0;i<=v-1;i++)
{
adjL[i]=(int *)calloc(sizeof(int),arr[i]);
}
index=(int *)calloc(v,sizeof(int));
while(fscanf(fp,"%d %d",&num1,&num2)!=EOF)
{
adjL[num1-1][index[num1-1]]=num2;
index[num1-1]++;
adjL[num2-1][index[num2-1]]=num1;
index[num2-1]++;
}
for(i=0;i<=v-1;i++)
{
printf("\n%d degree%d: ",i+1,arr[i]);
for(j=0;j<=arr[i]-1;j++)
{
printf(" %d ",adjL[i][j]);
}
}
printf("\n");
fclose(fp);
dfs(adjL);
getch();
return 0;
}
