[LeetCode] 24. Swap Nodes in Pairs - 문제풀이 Description 인접한 두개의 노드끼리 swap하여 반환하는 문제입니다. Given a linked list, swap every two adjacent nodes and return its head. You must solve the problem without modifying the values in the list's nodes (i.e., only nodes themselves may be changed.) Example 1: Input: head = [1,2,3,4] Output: [2,1,4,3] Example 2: Input: head = [] Output: [] Example 3: Input: head = [1] Output: [1] Constraints: The number of .. 알고리즘/LeetCode 2022. 2. 16. 11:13
[LeetCode] 136. Single Number - 문제풀이 Description 비어있지 않은 배열이 주어지고 하나의 원소만 한개의 값을 가지고 나머지는 2개씩 값을 가지고있을때 하나의 원소 반환하는 문제입니다. Given a non-empty array of integers nums, every element appears twice except for one. Find that single one. You must implement a solution with a linear runtime complexity and use only constant extra space. Example 1: Input: nums = [2,2,1] Output: 1 Example 2: Input: nums = [4,1,2,1,2] Output: 4 Example 3: Input.. 알고리즘/LeetCode 2022. 2. 15. 02:49
[LeetCode] 190. Reverse Bits - 문제풀이 Description 주어진 부호없는 32비트 정수를 뒤집어서 반환하는 문제입니다. Reverse bits of a given 32 bits unsigned integer. Note: Note that in some languages, such as Java, there is no unsigned integer type. In this case, both input and output will be given as a signed integer type. They should not affect your implementation, as the integer's internal binary representation is the same, whether it is signed or unsigned. In.. 알고리즘/LeetCode 2022. 2. 15. 02:09
[LeetCode] 191. Number of 1 Bits - 문제풀이 Description 주어진 정수의 bit(1)의 개수를 반환하는 문제입니다. Write a function that takes an unsigned integer and returns the number of '1' bits it has (also known as the Hamming weight). Note: Note that in some languages, such as Java, there is no unsigned integer type. In this case, the input will be given as a signed integer type. It should not affect your implementation, as the integer's internal binary repre.. 알고리즘/LeetCode 2022. 2. 15. 01:31
[LeetCode] 231. Power of Two - 문제풀이 Description 주어진수가 2의 제곱에 포함되는지 여부를 반환하는 문제입니다. Given an integer n, return true if it is a power of two. Otherwise, return false. An integer n is a power of two, if there exists an integer x such that n == 2x. Example 1: Input: n = 1 Output: true Explanation:2^0 = 1 Example 2: Input: n = 16 Output: true Explanation:2^4 = 16 Example 3: Input: n = 3 Output: false Constraints: -2^31 0010000 n-1 > 11.. 알고리즘/LeetCode 2022. 2. 14. 23:52
[LeetCode] 235. Lowest Common Ancestor of a Binary Search Tree - 문제풀이 Description 이진검색트리에서 주어진 두 노드의 가장 최하위 공통 조상 LCA를 찾아 반환하는 문제입니다. Given a binary search tree (BST), find the lowest common ancestor (LCA) of two given nodes in the BST. According to the definition of LCA on Wikipedia: “The lowest common ancestor is defined between two nodes p and q as the lowest node in T that has both p and q as descendants (where we allow a node to be a descendant of itself).” E.. 알고리즘/LeetCode 2022. 2. 14. 17:47
[LeetCode] 653. Two Sum IV - Input is a BST - 문제풀이 Description 주어진 유효한 이진검색트리에서 두개의 요소의 합이 k가 되는 경우가 있는지 여부를 반환하는 문제입니다. Given the root of a Binary Search Tree and a target number k, return true if there exist two elements in the BST such that their sum is equal to the given target. Example 1: Input: root = [5,3,6,2,4,null,7], k = 9 Output: true Example 2: Input: root = [5,3,6,2,4,null,7], k = 28 Output: false Constraints: The number of nodes in.. 알고리즘/LeetCode 2022. 2. 14. 14:23
[LeetCode] 701. Insert into a Binary Search Tree - 문제풀이 Description 주어진 이진 검색 트리에서 특정 값을 올바른 노드에 삽입 후 root를 반환하는 문제입니다. 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. Notice that there may exist multiple valid ways for the insertion, as long as the tree remains a BST after inserti.. 알고리즘/LeetCode 2022. 2. 14. 13:12
[LeetCode] 700. Search in a Binary Search Tree - 문제풀이 Description 주어진 이진검색트리(BST)에서 val와 같은 값을 가지는 노드를 반환하는 문제입니다. You are given the root of a binary search tree (BST) and an integer val. Find the node in the BST that the node's value equals val and return the subtree rooted with that node. If such a node does not exist, return null. Example 1: Input: root = [4,2,7,1,3], val = 2 Output: [2,1,3] Example 2: Input: root = [4,2,7,1,3], val = 5 Output: .. 알고리즘/LeetCode 2022. 2. 14. 02:40
[LeetCode] 78. Subsets - 문제풀이 Description Given an integer array nums of unique elements, return all possible subsets (the power set). The solution set must not contain duplicate subsets. Return the solution in any order. Example 1: Input: nums = [1,2,3] Output: [[],[1],[2],[1,2],[3],[1,3],[2,3],[1,2,3]] Example 2: Input: nums = [0] Output: [[],[0]] Constraints: 1 알고리즘/LeetCode 2022. 2. 13. 22:33
[Leetcode] 104. Maximum Depth of Binary Tree - 문제풀이 Description 주어진 이지트리의 최대 깊이를 찾는 문제입니다. Given the root of a binary tree, return its maximum depth. A binary tree's maximum depth is the number of nodes along the longest path from the root node down to the farthest leaf node. Example 1: Input: root = [3,9,20,null,null,15,7] Output: 3 Example 2: Input: root = [1,null,2] Output: 2 Constraints: The number of nodes in the tree is in the range [0, 104.. 알고리즘/LeetCode 2022. 2. 11. 18:04
[LeetCode] 560. Subarray Sum Equals K - 문제풀이 Description 주어진 배열에서 연속된 부분배열의 합이 k가 되는 모든 케이스를 반환하는 문제입니다. Given an array of integers nums and an integer k, return the total number of continuous subarrays whose sum equals to k. Example 1: Input: nums = [1,1,1], k = 2 Output: 2 Example 2: Input: nums = [1,2,3], k = 3 Output: 2 Constraints: 1 알고리즘/LeetCode 2022. 2. 11. 00:52
[LeetCode] 532. K-diff Pairs in an Array - 문제풀이 Description Given an array of integers nums and an integer k, return the number of unique k-diff pairs in the array. A k-diff pair is an integer pair (nums[i], nums[j]), where the following are true: 0 알고리즘/LeetCode 2022. 2. 9. 10:30
[LeetCode] 258. Add Digits - 문제풀이 Description 정수num이 주어졌을때 각 자리별로 한자리 수가 될때까지 더하여 반환하는 문제입니다. Given an integer num, repeatedly add all its digits until the result has only one digit, and return it. Example 1: Input: num = 38 Output: 2 Explanation: The process is 38 --> 3 + 8 --> 11 11 --> 1 + 1 --> 2 Since 2 has only one digit, return it. Example 2: Input: num = 0 Output: 0 Constraints: 0 알고리즘/LeetCode 2022. 2. 8. 10:15
[LeetCode] 389. Find the Difference - 문제풀이 Description s문자열을 무작위로 섞은뒤 하나의문자열을 추가해 만든 t가 있을때 추가된 문자를 구하는 문제입니다. You are given two strings s and t. String t is generated by random shuffling string s and then add one more letter at a random position. Return the letter that was added to t. Example 1: Input: s = "abcd", t = "abcde" Output: "e" Explanation: 'e' is the letter that was added. Example 2: Input: s = "", t = "y" Output: "y" Constra.. 알고리즘/LeetCode 2022. 2. 7. 11:38
[LeetCode] 102. Binary Tree Level Order Traversal - 문제풀이 Description 주어진 트리를 층별로 순회하며 순서대로 층별 요소의 목록을 반환하는 문제입니다. 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). Example 1: Input: root = [3,9,20,null,null,15,7] Output: [[3],[9,20],[15,7]] Example 2: Input: root = [1] Output: [[1]] Example 3: Input: root = [] Output: [] Constraints: The number of nodes in the tree is in.. 알고리즘/LeetCode 2022. 2. 6. 16:59
[LeetCode] 80. Remove Duplicates from Sorted Array II - 문제풀이 Description 주어진 오름차순으로 정렬된 배열에서 최대 2개 까지만 중복을 허용 하도록 재구성하여 반환하는 문제입니다. in-place로 추가 공간을 사용하지 않고 해결해야 합니다. Given an integer array nums sorted in non-decreasing order, remove some duplicates in-place such that each unique element appears at most twice. The relative order of the elements should be kept the same. Since it is impossible to change the length of the array in some languages, you must in.. 알고리즘/LeetCode 2022. 2. 6. 15:37
[LeetCode] 120. Triangle - 문제풀이 Description 주어진 삼각형형태의 array 목록에서 맨아래로 갈 수 있는 최단거리를 반환하는 문제입니다. Given a triangle array, return the minimum path sum from top to bottom. For each step, you may move to an adjacent number of the row below. More formally, if you are on index i on the current row, you may move to either index i or index i + 1 on the next row. Example 1: Input: triangle = [[2],[3,4],[6,5,7],[4,1,8,3]] Output: 11 Expl.. 알고리즘/LeetCode 2022. 2. 6. 13:01
[LeetCode] 198. House Robber - 문제풀이 Description 주어진 배열에서 연속된 위치의 값은 훔칠 수 없는 점을 감안하여 최대로 훔칠 수 있는 금액을 계산하는 문제입니다. You are a professional robber planning to rob houses along a street. Each house has a certain amount of money stashed, the only constraint stopping you from robbing each of them is that adjacent houses have security systems connected and it will automatically contact the police if two adjacent houses were broken into on .. 알고리즘/LeetCode 2022. 2. 5. 01:11
[LeetCode] 70. Climbing Stairs - 문제풀이 Description n높이의 계단을 1또는 2스텝을 한 번에 오를 수 있다고 가정할때 top으로 올라갈 수 있는 경우의 수를 계산하는 문제입니다. You are climbing a staircase. It takes n steps to reach the top. Each time you can either climb 1 or 2 steps. In how many distinct ways can you climb to the top? Example 1: Input: n = 2 Output: 2 Explanation: There are two ways to climb to the top. 1. 1 step + 1 step 2. 2 steps Example 2: Input: n = 3 Output: 3 Ex.. 알고리즘/LeetCode 2022. 2. 5. 00:09
