Leetcode Solutions

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  [Solved] There are n rooms labeled from 0 to n – 1 and all the rooms are locked except for room 0. Your goal is to visit all the rooms. However, you cannot enter a locked room without having its key.

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  [Solved] Given an n x n binary matrix image, flip the image horizontally, then invert it, and return the resulting image. To flip an image horizontally means that each row of the image is reversed.

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  [Solved] You are given a string sentence that consist of words separated by spaces. Each word consists of lowercase and uppercase letters only. We would like to convert the sentence to “Goat Latin” (a made-up language similar to Pig Latin.) The rules of Goat Latin are as follows:

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  [Solved] Given a string s and a character c that occurs in s, return an array of integers answer where answer.length == s.length and answer[i] is the distance from index i to the closest occurrence of character c in s.

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  [Solved] Given the root of a binary tree, return the same tree where every subtree (of the given tree) not containing a 1 has been removed. A subtree of a node node is node plus every node that is a descendant of node.

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  [Solved] A website domain “discuss.leetcode.com” consists of various subdomains. At the top level, we have “com”, at the next level, we have “leetcode.com” and at the lowest level, “discuss.leetcode.com”. When we visit a domain like “discuss.leetcode.com”, we will also visit the parent domains “leetcode.com” and “com” implicitly.

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  [Solved] You are given a string s of lowercase English letters and an array widths denoting how many pixels wide each lowercase English letter is. Specifically, widths[0] is the width of ‘a’, widths[1] is the width of ‘b’, and so on.

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  [Solved] International Morse Code defines a standard encoding where each letter is mapped to a series of dots and dashes, as follows: ‘a’ maps to “.-“, ‘b’ maps to “-…”,

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  [Solved] An integer x is a good if after rotating each digit individually by 180 degrees, we get a valid number that is different from x. Each digit must be rotated – we cannot choose to leave it alone.

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  [Solved] Given a string s, you can transform every letter individually to be lowercase or uppercase to create another string. Return a list of all possible strings we could create. Return the output in any order.

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  [Solved] You’re given strings jewels representing the types of stones that are jewels, and stones representing the stones you have. Each character in stones is a type of stone you have. You want to know how many of the stones you have are also jewels.

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  [Solved] Given an m x n matrix, return true if the matrix is Toeplitz. Otherwise, return false. A matrix is Toeplitz if every diagonal from top-left to bottom-right has the same elements.

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  [Solved] You are given an integer array cost where cost[i] is the cost of ith step on a staircase. Once you pay the cost, you can either climb one or two steps. You can either start from the step with index 0, or the step with index 1.

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  [Solved] Given a characters array letters that is sorted in non-decreasing order and a character target, return the smallest character in the array that is larger than target.

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  [Solved] Given an array of integers temperatures represents the daily temperatures, return an array answer such that answer[i] is the number of days you have to wait after the ith day to get a warmer temperature.

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  [Solved] A self-dividing number is a number that is divisible by every digit it contains.

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  [Solved] Given a string s, return the string after replacing every uppercase letter with the same lowercase letter.

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  [Solved] Given an array of integers nums which is sorted in ascending order, and an integer target, write a function to search target in nums. If target exists, then return its index. Otherwise, return -1.

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  [Solved] Design a class to find the kth largest element in a stream. Note that it is the kth largest element in the sorted order, not the kth distinct element.

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  [Solved] You are given the root node of a binary search tree (BST) and a value to insert into the tree. Return the root node of the BST after the insertion. It is guaranteed that the new value does not exist in the original BST.