Add 1 to the list

Problem tc :O(n), sc:O(1) /* class Node{ int data; Node next; Node(int x){ data = x; next = null; } } */ class Solution { public Node addOne(Node head) { // code here. //reverse the list //add 1 ///reverse back again and return Node reverseNode = reverse(head); head = reverseNode; Node prev = null; int carry = 1; while(head!=null && carry!=0){ if(head.data + carry > 9){ int val = head.data + carry; head.data = (val) % 10; carry = (val)/10; } else { head.data = head.data+carry; carry =0; } prev = head; head = head.next; } if(carry!=0){ prev.next = new Node(carry); } return reverse(reverseNode); } public Node reverse(Node node){ Node prev = null; while(node!=null){ Node next = node.next; node.next = prev; prev = node; node = next; } return prev; } }

Apr 6, 2025 - 14:12

tc :O(n), sc:O(1)

/*
class Node{
    int data;
    Node next;

    Node(int x){
        data = x;
        next = null;
    }
}
*/

class Solution {
    public Node addOne(Node head) {
        // code here.
        //reverse the list
        //add 1
        ///reverse back again and return
        Node reverseNode = reverse(head);

        head = reverseNode;
        Node prev = null;
        int carry = 1;

        while(head!=null && carry!=0){
            if(head.data + carry > 9){
                int val  = head.data + carry;
                head.data = (val) % 10;
                carry = (val)/10;
            }
            else {
                head.data = head.data+carry;
                carry  =0;
            }
            prev = head;
            head = head.next;
        }

        if(carry!=0){
            prev.next = new Node(carry);
        }
        return reverse(reverseNode);
    }
    public Node reverse(Node node){
        Node prev = null;
        while(node!=null){
            Node next = node.next;
            node.next = prev;
            prev = node;
            node = next;
        }
        return prev;
    }
}