Add Two Numbers

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Let’s discuss a problem add two numbers as lists and their java code.

Given two non-empty linked lists representing two non-negative integers. The digits are stored in reverse order, and each of their nodes contains a single digit. We have to write a code to add these two numbers and return the sum as a linked list.

For this problem, you may assume the two numbers do not contain any leading zero, except the number 0 itself.

For example –

Linked List 1 : 2 -> 4 -> 6 -> NULL

Linked List 2 : 5 -> 6 -> 4 -> NULL

Result : 7 -> 0 -> 1 -> 1 -> NULL

Explanation :

In this example first, we added 2 and 5 the result is 7. Then, 6 and 4 the result is 10, so we put 0 and take 1 as a carry. Then, we added 6, 4, and 1 (carry) the result is 11, so we put 1 and take 1 as a carry.

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Plus One | Add One to Number Represented as Array

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In this problem, We have given a non-empty array which represents a non-negative integer. Write a code to add one to the number.

Each element in the array contain a single digit. You may assume the integer does not contain any leading zero, except the number 0 itself.

Example 1 –

Input:  [1, 3, 4]

Output: [1, 3, 5]

In this example, the array represents the number 134. When we add 1 to it, the new number is 135.

Example 2 –

Input : [1, 2, 9]

Output: [1, 3, 0]

The number is 129. When we add 1 to 129. The new number is 130.

Example 3 –

Input : [9, 9, 9]

Output: [1, 0, 0, 0]

For the number 999, when you add 1, the new number would be 1000. If you think in terms of array, the new array size would be the previous array size plus one.

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Valid Palindrome II | Delete at Most One Character to Make it a Palindrome

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In this tutorial, I am going to discuss a variation of palindrome questions valid palindrome II. In this problem, we can remove a character from a string to make it a palindrome.

Given a non-empty string, We may delete at most one character from a string. We have to write a code which checks whether we can make this string palindrome or not.

For example –

Example 1:

Input : “aba”
Output: true

This string is already palindrome. So we return true.

Example 2:

Input : “abca”
Output: true

This string is not a palindrome. But, if we delete either a character b or c from this string then the new string is a palindrome.

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