Implement singly linked list of integers using array

/* Implement singly linked list of integers using array */


#include <stdio.h>
#include <string.h>
#define MAX 30
typedef struct list
 { int head; //index of the front element
   int data[MAX];
   int next[MAX];//index of the successor
   int flag[MAX];//flag[i] as 0 indicates absence of data
 }list;
void insert( list *p,int position,int x);
void Delete(list *p,int position);
int  search(list *p,int x);
void print(list *p);
void read(list *p);
void init(list *p);

 int main()
  { list l;
    int x,op,position;
        do{
       fflush(stdin);
       printf("\n1)create\n2)insert\n3)delete\n4)search\n5)print\n6)quit");
       printf("\nEnter Your Choice:");
       scanf("%d",&op);
       switch(op)
{ case 1: read(&l);
 break;
 case 2: printf("\n enter the position and the data to be inserted : ");
 scanf("%d%d",&position,&x);
 insert(&l,position,x);
 break;
 case 3:printf("\n enter the position : ");
scanf("%d",&position);
Delete(&l,position);
break;
 case 4: printf("\nenter the number to be searched:");
 scanf("%d",&x);
 position=search(&l,x);
 if(position==-1)
    printf("\nnot found");
 else
   printf("Found at the position : %d",position+1);

break;
 case 5: print(&l);
 break;
 default:break;
}
    }while(op!=6);
  }


void  insert( list *p,int position,int x)
{ int i,j,pred;
 //locate an empty location
 for(j=0;p->flag[j]==1 && j<MAX  ;j++);
 if(j==MAX)
   {
printf("\nOverflow....");
return;
    }

 p->data[j]=x;
 p->flag[j]=1;
 if(position==1)
   {
p->next[j]=p->head;
p->head=j;
return;
    }
 //locate the predecessor
 for(pred=p->head,i=1;i<position-1;i++)
     {
if(pred==-1 || p->next[pred]==-1)
 {
printf("\nOverflow...");
return;
  }
 else
   pred=p->next[pred];
      }
  p->next[j]=p->next[pred];
  p->next[pred]=j;
     }

void  Delete(list *p,int position)//delete a data from given position
      {
int i,j,pred;
if(p->head==-1 || position <1)
  {
printf("\nUnderflow...can not delete ");
return;
  }
if(position==1)//first data to be deleted
   {
p->flag[p->head]=0;
p->head=p->next[p->head];
return;
   }
 //locate the predecessor
 for(pred=p->head,i=1;i<position-1;i++)
     {
if(pred==-1 || p->next[pred]==-1)
 {
printf("\nUnderflow...");
return;
  }
 else
   pred=p->next[pred];
      }
  j=p->next[pred];//index of the element to be deleted
  p->next[pred]=p->next[j];
  p->flag[j]=0;
     }

int   search(list *p,int x)
       { int i,  position=0;
if(p->head==-1)
return(-1);
for(i=p->head;i!=-1;i=p->next[i],position++)
if(x==p->data[i])
return(position);
return(-1);
       }
void print(list *p)
       { int i;
 printf("\n");
 for(i=p->head;i!=-1;i=p->next[i])
    printf("%d   ",p->data[i]);
       }
void read(list  *p)
   { int i,n;
     printf("\nEnter No. of data : ");
     scanf("%d",&n);
     printf("\Enter data : ");
     for(i=0;i<n;i++)
       {
scanf("%d", &(p->data[i]));
p->next[i]=i+1;
p->flag[i]=1;
       }
     p->next[n-1]=-1;
     p->head=0;
   }
void init(list *p)
  {
     int i;
     for(i=0;i<MAX;i++)
{
p->flag[i]=0;
p->next[i]=-1;
}
     p->head=-1;
   }