Jackson.tmm

LeetCode 1268 - Search Suggestions System Given an integer array nums and an integer k, return the kth largest element in the array. Note that it is the kth largest element in the sorted order, not the kth distinct element. example: Input: nums = [3,2,1,5,6,4], k = 2 Output: 5 Input: nums = [3,2,3,1,2,4,5,5,6], k = 4 Output: 4 How can we solve this problem? 這題要我們

LeetCode 1642 - Furthest Building You Can Reach You are given an integer array heights representing the heights of buildings, some bricks, and some ladders. You start your journey from building 0 and move to the next building by possibly using bricks or ladders. While moving from building i to building i+1 (0-indexed), If the current building’s height is greater than or equal to the next building’s height, you do

820 - Short Encoding of Words A valid encoding of an array of words is any reference string s and array of indices indices such that: words.length == indices.length The reference string s ends with the '#' character. For each index indices[i], the substring of s starting from indices[i] and up to (but not including) the next '#' character is equal to words[i]. Given an array of words, return the

LeetCode 5 - Longest Palindromic Substring Given a string s, return the longest palindromic substring in s. example Input: s = "babad" Output: "bab" Explanation: "aba" is also a valid answer. Input: s = "cbbd" Output: "bb" How can we solve this problem? 要解決這題，我們必須要先知道什麼是Palindrome

LeetCode 216 - Combination Sum III Find all valid combinations of k numbers that sum up to n such that the following conditions are true: Only numbers 1 through 9 are used. Each number is used at most once. Return a list of all possible valid combinations. The list must not contain the same combination twice, and the combinations may be returned in any order. example Input: k = 3,

LeetCode 17 - Letter Combinations of a Phone Number Given a string containing digits from 2-9 inclusive, return all possible letter combinations that the number could represent. Return the answer in any order. A mapping of digit to letters (just like on the telephone buttons) is given below. Note that 1 does not map to any letters. example Input: digits = "23" Output: ["ad","ae","af","bd","be","bf","cd","ce","cf"] Input: digits = "" Output: []

LeetCode 341 - Flatten Nested List Iterator You are given a nested list of integers nestedList. Each element is either an integer or a list whose elements may also be integers or other lists. Implement an iterator to flatten it. Implement the NestedIterator class: NestedIterator(List<NestedInteger> nestedList) Initializes the iterator with the nested list nestedList. int next() Returns the next integer in the nested list. boolean hasNext() Returns true if there

LeetCode 456 - 132 Pattern Given an array of n integers nums, a 132 pattern is a subsequence of three integers nums[i], nums[j] and nums[k] such that i < j < k and nums[i] < nums[k] < nums[j]. Return true if there is a 132 pattern in nums, otherwise, return false. example Input: nums = [1,2,3,4] Output: false Explanation: There is no 132 pattern in the sequence. Input: nums =

LeetCode 1209 - Remove All Adjacent Duplicates in String II You are given a string s and an integer k, a k duplicate removal consists of choosing k adjacent and equal letters from s and removing them, causing the left and the right side of the deleted substring to concatenate together. We repeatedly make k duplicate removals on s until we no longer can. Return the final string after all

LeetCode 225 - Implement Stack using Queues Implement a last-in-first-out (LIFO) stack using only two queues. The implemented stack should support all the functions of a normal stack (push, top, pop, and empty). Implement the MyStack class: void push(int x) Pushes element x to the top of the stack. int pop() Removes the element on the top of the stack and returns it. int top() Returns the element on the