수쿵의 IT월드

문제Given an array of distinct integers candidates and a target integer target, return a list of all unique combinations of candidates where the chosen numbers sum to target. You may return the combinations in any order.The same number may be chosen from candidates an unlimited number of times. Two combinations are unique if the frequency of at least one of the chosen numbers is different.The test..

문제Given a positive integer n, write a function that returns the number of set bits in its binary representation (also known as the Hamming weight). Example 1:Input: n = 11Output: 3Explanation:The input binary string 1011 has a total of three set bits. Example 2:Input: n = 128Output: 1Explanation:The input binary string 10000000 has a total of one set bit. Example 3:Input: n = 2147483645Output: 3..

문제A phrase is a palindrome if, after converting all uppercase letters into lowercase letters and removing all non-alphanumeric characters, it reads the same forward and backward. Alphanumeric characters include letters and numbers.Given a string s, return true if it is a palindrome, or false otherwise. Example 1:Input: s = "A man, a plan, a canal: Panama"Output: trueExplanation: "amanaplanacanal..

문제Given the root of a binary tree, determine if it is a valid binary search tree (BST).A valid BST is defined as follows:The left subtree of a node contains only nodes with keys strictly less than the node's key.The right subtree of a node contains only nodes with keys strictly greater than the node's key.Both the left and right subtrees must also be binary search trees. Example 1:Input: root = ..

문제Given 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 + 1 = 0.nums[1] + nums[2] + nums[4] = 0 + 1 + (-1) = 0..

문제Given an integer array nums, return an array answer such that answer[i] is equal to the product of all the elements of nums except nums[i].The product of any prefix or suffix of nums is guaranteed to fit in a 32-bit integer.You must write an algorithm that runs in O(n) time and without using the division operation. Example 1:Input: nums = [1,2,3,4]Output: [24,12,8,6] Example 2:Input: nums = [-..

문제You 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 = 2Output: 2Explanation: There are two ways to climb to the top.1. 1 step + 1 step2. 2 steps Example 2:Input: n = 3Output: 3Explanation: There are three ways to climb to the top.1. 1 step + 1 step + 1 step2. 1 step +..