### Longest Common Prefix - Leet Code Solution

Problem Statement Write a function to find the longest common prefix string…

July 23, 2019

You are given two non-empty linked lists representing two non-negative integers. The digits are stored in reverse order and each of their nodes contain a single digit. Add the two numbers and return it as a linked list.

You may assume the two numbers do not contain any leading zero, except the number 0 itself.

```
Example:
Input: (2 -> 4 -> 3) + (5 -> 6 -> 4)
Output: 7 -> 0 -> 8
Explanation: 342 + 465 = 807.
```

```
private static ListNode addTwoNumbersHelper(ListNode l1, ListNode l2, int carry) {
if (l1 == null && l2 == null && carry == 0) {
return null;
}
int sum = carry;
if (l1 != null) { sum += l1.val; }
if (l2 != null) { sum += l2.val; }
if (sum > 9) {
sum = sum - 10;
carry = 1;
}
else {
carry = 0;
}
ListNode newNode = new ListNode(sum);
newNode.next = addTwoNumbersHelper(l1 != null ? l1.next : null, l2 != null ? l2.next : null, carry);
return newNode;
}
public static ListNode addTwoNumbers(ListNode l1, ListNode l2) {
return addTwoNumbersHelper(l1, l2, 0);
}
```

This problem is rather simple. Since, the number is represented as link list in reverse order. i.e. the first node represent the last digit of a number. So, you can just started adding number as you traverse the two link list.

- Start with iterating both link list.
- take sum of two nodes, and carry if previously set.
- If the sum is more than single digit, set the carry.
- Now, new sum is our new node.
- Since, it will be last digit in the result number, and will be first node in link list.
- Its next pointer will be the one which will come out in next round of sum.
- So, we simply set its next and call same method in recursive manner. Which will again goes in recursive mode untill all link list is exhausted.
- And, we get our link list as sum.

Problem Statement Write a function to find the longest common prefix string…

Here are some tips while preparing for your coding interviews. 1. Do study or…

Problem Statement Say you have an array prices for which the ith element is the…

Problem Statement Given an array, rotate the array to the right by k steps…

A Binary tree is a data structure which has two children nodes attached to it…

Problem Statement You are given an array of integers. And, you have find the…

Problem Statement You are given a string text of words that are placed among…

Problem Statement You are given a rows x cols matrix grid. Initially, you are…

Problem Statement Given a string s, return the maximum number of unique…

Problem The Leetcode file system keeps a log each time some user performs a…

Problem Statement Replace all spaces in a string with ‘%20’ (three characters…

Problem Implement an algorithm to determine if a string has all the characters…