MiddleElementofLinkList.cpp

/*
Middle element of linked list
Given a linked list of integers. Find and return the middle element of the linked list. Note: If there are N nodes in the linked list and N is even then return the (N/2+1)th element. 
Input Format
The only argument given head pointer of linked list.
Output Format
Return the middle element of the linked list.
Constraints
1 <= length of the linked list <= 100000
1 <= Node value <= 10^9 
For Example
Input 1:
    1->2->3->4->5
Output 1:
   3 

Input 2:
    A = 1->5->6->2->3->4
Output 2:
    2
*/

//Use two pointer fast and slow fast reaches null or fast->next reaches null slow points to mid

/**
 * Definition for singly-linked list.
 * struct ListNode {
 *     int val;
 *     ListNode *next;
 *     ListNode(int x) : val(x), next(NULL) {}
 * };
 */
int Solution::solve(ListNode* A) {
    ListNode *slow=A, *fast=A;
    while(fast!=NULL && fast->next!=NULL){
        fast=fast->next->next;
        slow=slow->next;
    }
    return slow->val;
}