Create problem3.c

Author: rmkcodingclub

problem3.c

@@ -0,0 +1,127 @@
+#include<stdio.h>
+#include<stdlib.h>
+
+/* Link list node */
+struct node
+{
+  int data;
+  struct node* next;
+};
+
+/* Function to get the counts of node in a linked list */
+int getCount(struct node* head);
+
+/* function to get the intersection point of two linked
+   lists head1 and head2 where head1 has d more nodes than
+   head2 */
+int _getIntesectionNode(int d, struct node* head1, struct node* head2);
+
+/* function to get the intersection point of two linked
+   lists head1 and head2 */
+int getIntersectionNode(struct node* head1, struct node* head2)
+{
+  int c1 = getCount(head1);
+  int c2 = getCount(head2);
+  int d;
+
+  if(c1 > c2)
+  {
+    d = c1 - c2;
+    return _getIntesectionNode(d, head1, head2);
+  }
+  else
+  {
+    d = c2 - c1;
+    return _getIntesectionNode(d, head2, head1);
+  }
+}
+
+/* function to get the intersection point of two linked
+   lists head1 and head2 where head1 has d more nodes than
+   head2 */
+int _getIntesectionNode(int d, struct node* head1, struct node* head2)
+{
+  int i;
+  struct node* current1 = head1;
+  struct node* current2 = head2;
+
+  for(i = 0; i < d; i++)
+  {
+    if(current1 == NULL)
+    {  return -1; }
+    current1 = current1->next;
+  }
+
+  while(current1 !=  NULL && current2 != NULL)
+  {
+    if(current1 == current2)
+      return current1->data;
+    current1= current1->next;
+    current2= current2->next;
+  }
+
+  return -1;
+}
+
+/* Takes head pointer of the linked list and
+   returns the count of nodes in the list */
+int getCount(struct node* head)
+{
+  struct node* current = head;
+  int count = 0;
+
+  while (current != NULL)
+  {
+    count++;
+    current = current->next;
+  }
+
+  return count;
+}
+
+/* Main func is to quickly test the above function*/
+   
+int main()
+{
+  /*
+    Create two linked lists
+
+    1st 3->6->9->15->30
+    2nd 10->15->30
+
+    15 is the intersection point
+  */
+
+  struct node* newNode;
+  struct node* head1 =
+            (struct node*) malloc(sizeof(struct node));
+  head1->data  = 10;
+
+  struct node* head2 =
+            (struct node*) malloc(sizeof(struct node));
+  head2->data  = 3;
+
+  newNode = (struct node*) malloc (sizeof(struct node));
+  newNode->data = 6;
+  head2->next = newNode;
+
+  newNode = (struct node*) malloc (sizeof(struct node));
+  newNode->data = 9;
+  head2->next->next = newNode;
+
+  newNode = (struct node*) malloc (sizeof(struct node));
+  newNode->data = 15;
+  head1->next = newNode;
+  head2->next->next->next  = newNode;
+
+  newNode = (struct node*) malloc (sizeof(struct node));
+  newNode->data = 30;
+  head1->next->next= newNode;
+
+  head1->next->next->next = NULL;
+
+  printf("\n The node of intersection is %d \n",
+          getIntersectionNode(head1, head2));
+
+  getchar();
+}