You can read the full story on The Swift Nerd blog with the link above.

Problem Description

You are given an m x n binary matrix grid. An island is a group of 1's (representing land) connected 4-directionally (horizontal or vertical.) You may assume all four edges of the grid are surrounded by water.

The area of an island is the number of cells with a value 1 in the island.

Return the maximum area of an island in grid. If there is no island, return 0.

Example 1:

Read the full story on The Swift Nerd blog with the link above.

Problem Description

Evaluate the value of an arithmetic expression in Reverse Polish Notation.

Valid operators are +, -, *, and /. Each operand may be an integer or another expression.

Note that division between two integers should truncate toward zero.

It is guaranteed that the given RPN expression is always valid. That means the expression would always evaluate to a result, and there will not be any division by zero operation.

Examples

Input: tokens = ["2","1","+","3","*"]
Output: 9
Explanation: ((2 + 1) * 3) = 9Input: tokens = ["4","13","5","/","+"]
Output…

Check out the full story on The Swift Nerd blog with the link above.

Problem Description

Given a list of strings words and a string pattern, return a list of words[i] that match pattern. You may return the answer in any order.

A word matches the pattern if there exists a permutation of letters p so that after replacing every letter x in the pattern with p(x), we get the desired word.

Recall that a permutation of letters is a bijection from letters to letters: every letter maps to another letter, and no two letters map to the same letter.

Examples

Input: words…

You can read the full story on The Swift Nerd blog with the link above.

Problem Description

Given the root of a binary tree, return the level order traversal of its nodes’ values. (i.e., from left to right, level by level).

Examples

You can read the full story on The Swift Nerd blog with the link above.

Problem Description

Given an integer array nums of size n, return the minimum number of moves required to make all array elements equal.

In one move, you can increment or decrement an element of the array by 1.

Examples

Input: nums = [1,2,3]
Output: 2
Explanation:
Only two moves are needed (remember each move increments or decrements one element):
[1,2,3]  =>  [2,2,3]  =>  [2,2,2]Input: nums = [1,10,2,9]
Output: 16

Constraints

• n == nums.length
• 1 <= nums.length <= 105
• -109 <= nums[i] <= 109

Solution

One brute force approach can…

If you are preparing for coding interviews, then check the amazing Swift Leetcode series on The Swift Nerd blog.

Problem Description

Given a list of words, each word consists of English lowercase letters.

Let’s say word1 is a predecessor of word2 if and only if we can add exactly one letter anywhere in word1 to make it equal to word2. For example, "abc" is a predecessor of "abac".

A word chain is a sequence of words [word_1, word_2, ..., word_k] with k >= 1, where word_1 is a predecessor of word_2, word_2 is a predecessor of word_3, and so on.

Return the…

You checkout the full story on The Swift Nerd blog with the link above.

Problem Description

A valid number can be split up into these components (in order):

1. A decimal number or an integer.
2. (Optional) An 'e' or 'E', followed by an integer.

A decimal number can be split up into these components (in order):

1. (Optional) A sign character (either '+' or '-').
2. One of the following formats:
3. At least one digit, followed by a dot '.'.
4. At least one digit, followed by a dot '.', followed by at least one digit.
5. A dot '.', followed by at least one digit.

An…

Check the full story on The Swift Nerd blog with the link above.

Problem Description

Given the root of a binary tree, flatten the tree into a “linked list”:

• The “linked list” should use the same TreeNode class where the right child pointer points to the next node in the list and the left child pointer is always null.
• The “linked list” should be in the same order as a pre-order traversal of the binary tree.

Examples