leetcode patterns

Given n non-negative integers representing an elevation map where the width of each bar is 1, compute how much water it can trap after raining. Input: height = [0,1,0,2,1,0,1,3,2,1,2,1] Output: 6 Explanation: The above elevation map (black section) is represented by array [0,1,0,2,1,0,1,3,2,1,2,1]. In this case, 6 units of rain water (blue section) are being trapped. CPP solution … Read more

Given the root of a binary tree, determine if it is a valid binary search tree (BST). A valid BST is defined as follows: Input: root = [2,1,3] Output: true Solution : Java DFS : Python : CPP : Inorder solution :

Two integer arrays, nums and multipliers, of sizes n and m, respectively, are provided to you, where n >= m. The arrays are all one-dimensional. You start with a score of zero. You need to carry out precisely m operations. On the ith (1-indexed) action, you will: Choose one integer x from the beginning or … Read more

Given an integer array nums, return all the triplets [nums[i], nums[j], nums[k]] such that i != j, i != k, and j != k, and nums[i] + nums[j] + nums[k] == 0. Notice that the solution set must not contain duplicate triplets. Example 1: Input: nums = [-1,0,1,2,-1,-4] Output: [[-1,-1,2],[-1,0,1]] Explanation: nums[0] + nums[1] + nums[2] = (-1) + 0 + … Read more

Given a string s, return the longest palindromic substring in s. A string is called a palindrome string if the reverse of that string is the same as the original string. Example 1: Input: s = “babad” Output: “bab” Explanation: “aba” is also a valid answer. Example 2: Input: s = “cbbd” Output: “bb” Solution : JavaScript : CPP … Read more

Find the length of the longest substring without repeated characters given a string s. Example 1: Input: s = “abcabcbb” Output: 3 Explanation: The answer is “abc”, with the length of 3. Example 2: Input: s = “bbbbb” Output: 1 Explanation: The answer is “b”, with the length of 1. Example 3: Input: s = … Read more

You are given two non-empty linked lists that each represent a non-negative integer. The digits are kept in reverse order, with each node containing only one digit. Add the two numbers together and return the total as a linked list. Except for the number 0 itself, you may presume that the two numbers do not … Read more

Provide the median of the two sorted arrays given two sorted arrays of sizes m and n, respectively. The entire complexity of the run time should be O(log (m+n)). Eg 1: Numbers1 = [1,3], Numbers2 = [2] Result: 2.00000 Explanation: the merged array equals [1,2,3], and the median is 2. Eg 2: Numbers1 = [1,2], … Read more

Sure, let’s solve the “Two Sum” problem using different approaches in C++, Python, Java, and JavaScript, and add some humor along the way! We’ll explore the bruteforce, hashmap, two hashmap, and two-pointer methods for each language. Time Complexity: C++: 1. Brute Force Approach: Notice: This approach has a time complexity of O(n^2), which isn’t very … Read more