Kth Element from The Last

Author: akashmodak97

Hacker Blocks/Kth Element from The Last.cpp

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+/* Hacker Blocks */
+/* Title - Kth Element from The Last */
+/* Created By - Akash Modak */
+/* Date - 2/8/2020 */
+
+// Given a linked list with n nodes. Find the kth element from last without computing the length of the linked list.
+
+// Input Format
+// First line contains space separated integers representing the node values of the linked list. The list ends when the input comes as '-1'. The next line contains a single integer k.
+
+// Constraints
+// n < 10^5
+
+// Output Format
+// Output a single line containing the node value at the kth element from last.
+
+// Sample Input
+// 1 2 3 4 5 6 -1
+// 3
+// Sample Output
+// 4
+// Explanation
+// The linked list is 1 2 3 4 5 6. -1 is not included in the list. So the third element from the last is 4
+
+#include<iostream>
+using namespace std;
+class Node{
+	public:
+	int data;
+	Node* next;
+	Node(int d){
+		this->data=d;
+		this->next=NULL;
+	}
+};
+void buildlist(Node* &head,int data){
+	if(head==NULL){
+		Node *temp = new Node(data);
+		head = temp;
+		return;
+	}
+	Node *c = head;
+	while(c->next!=NULL)
+	c=c->next;
+	Node * temp= new Node(data);
+	c->next = temp;
+	return;
+}
+
+int main() {
+	Node *head = NULL;
+	int temp1;
+	cin>>temp1;
+	while(temp1!=-1){
+		buildlist(head,temp1);
+		cin>> temp1;
+	}
+	int k;
+	cin>>k;
+	Node * temp;
+	temp=head;
+	while(k--){
+		temp=temp->next;
+	}
+	Node * slow = head;
+	while(temp!=NULL)
+	{
+		temp=temp->next;
+		slow=slow->next;
+	}
+	cout<<slow->data<<endl;
+	return 0;
+}