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Python130

LeetCode 2. Add Two Numbers [Linked List] Problem: 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.. 2020. 6. 9.
LeetCode. First Bad Version [Sorting and Searching] Problem: You are a product manager and currently leading a team to develop a new product. Unfortunately, the latest version of your product fails the quality check. Since each version is developed based on the previous version, all the versions after a bad version are also bad. Suppose you have n versions [1, 2, ..., n] and you want to find out the first bad one, which causes all the following o.. 2020. 6. 8.
LeetCode. Merge Sorted Array [Sorting and Searching] Problem: Given two sorted integer arrays nums1 and nums2, merge nums2 into nums1 as one sorted array. Note: The number of elements initialized in nums1 and nums2 are m and n respectively. You may assume that nums1 has enough space (size that is greater or equal to m + n) to hold additional elements from nums2. Example: Input: nums1 = [1,2,3,0,0,0], m = 3 nums2 = [2,5,6], n = 3 Output: [1,2,2,3,5.. 2020. 6. 8.
LeetCode. Convert Sorted Array to Binary Search Tree [Trees] Problem: Given an array where elements are sorted in ascending order, convert it to a height balanced BST. For this problem, a height-balanced binary tree is defined as a binary tree in which the depth of the two subtrees of every node never differ by more than 1. Example: -Summary- Solve by recursive function call 1. First, find a root first by finding the midpoint of the given integer array. 2.. 2020. 6. 7.
LeetCode. Binary Tree Level Order Traversal [Trees] Problem: Given a binary tree, return the level order traversal of its nodes' values. (ie, from left to right, level by level). For example: Given binary tree [3,9,20,null,null,15,7], -Summary- Solve by BFS (Breadth-First Search) Algorithm using queue 1. Create a queue and keep adding the value if left or right subtree exists 2. While adding the value to the queue, we pop and add the value to the.. 2020. 6. 7.
LeetCode. Symmetric Tree [Trees] Problem: Given a binary tree, check whether it is a mirror of itself (ie, symmetric around its center). For example, this binary tree [1,2,2,3,4,4,3] is symmetric: But the following [1,2,2,null,3,null,3] is not: -Summary- 1. If a tree has no root or root itself exist, it will always return True 2. Otherwise, we keep check below condition recursively of the Tree's left and right subtree - leftSub.. 2020. 6. 7.

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