How to find the maximum element from the linked list? - c

Question

This is what I have tried so far.
#include<stdlib.h>
struct node
{
int data;
struct node *next;
};
void create(struct node **q)
{
struct node *r,*t;
int cnt,i,dat;
printf("How many nodes?");
scanf("%d",&cnt);
for(i=0;i<cnt;i++)
{
printf("Enter the data %d ",i);
scanf("%d",&dat);
r=(struct node *) malloc (sizeof(struct node));
r->data=dat;
r->next=NULL;
if(*q==NULL)
{
*q=r;
}
else
{
t=*q;
while(t->next!=NULL)
{
t=t->next;
}
t->next=r;
}
}
}
void display(struct node **q)
{
struct node *r;
r=*q;
while(r!=NULL)
{
printf("%d->",r->data);
r=r->next;
}
printf("\n");
}
void max(struct node **q)
{
struct node *r;
int max=0;
r=*q;
while((r->next)!=NULL)
{
max=r->data;
r=r->next;
if((r->data)>max)
{
max=r->data;
}
}
printf("The max is %d",max);
printf("\n");
}
int main()
{
struct node *head;
create(&head);
display(&head);
max(&head);
}
If I use the numbers 1, 2, and 3 as input my program currently incorrectly detects 2 as the maximum element. How can I fix it so that it will correctly determine 3 to be the maximum element?
rutuparna#pucsd-rutuparna:~/C/Datastructures assignment$ gcc linkedmax.c
rutuparna#pucsd-rutuparna:~/C/Datastructures assignment$ ./a.out
How many nodes?3
Enter the data 0 3
Enter the data 1 2
Enter the data 2 1
3->2->1->
The max is 2

Answer 1

There are a few issues with the loop
while((r->next)!=NULL) {
max=r->data;
r=r->next;
if((r->data)>max) {
max=r->data;
}
}
The line max=r->data unconditionally updates max. Combining this with the fact that the test (r->next)!=NULL causes your loop to exit one item early, the loop currently always returns the value of the second last item.
The code should be changed to something like
while(r!=NULL) {
if(r->data>max) {
max=r->data;
}
r=r->next;
}