medium

ProblemThere are n rooms labeled from 0 to n - 1 and all the rooms are locked except for room 0. Your goal is to visit all the rooms. However, you cannot enter a locked room without having its key. When you visit a room, you may find a set of distinct keys in it. Each key has a number on it, denoting which room it unlocks, and you can take all of them with you to unlock the other rooms. Given an array rooms where rooms[i] is the set of keys that you can obtain if you visited room i, return true  ...

ProblemGiven a binary array nums, you should delete one element from it. Return the size of the longest non-empty subarray containing only 1‘s in the resulting array. Return 0 if there is no such subarray. Example 1: 1234Input: nums = [1,1,0,1]Output: 3Explanation: After deleting the number in position 2, [1,1,1] contains 3 numbers with value of 1's. Example 2: 1234Input: nums = [0,1,1,1,0,1,1,0,1]Output: 5Explanation: After deleting the number in position 4, [0,1,1,1,1,1,0,1] longest suba ...

ProblemGiven a string s and an integer k, return the maximum number of vowel letters in any substring of s with length k. Vowel letters in English are 'a', 'e', 'i', 'o', and 'u'. Example 1: 1234Input: s = "abciiidef", k = 3Output: 3Explanation: The substring "iii" contains 3 vowel letters. Example 2: 1234Input: s = "aeiou", k = 2Output: 2Explanation: Any substring of length 2 contains 2 vowels. Example 3: 1234Input: s = &qu ...

ProblemGiven an array of intervals intervals where intervals[i] = [starti, endi], return the minimum number of intervals you need to remove to make the rest of the intervals non-overlapping. Example 1: 1234Input: intervals = [[1,2],[2,3],[3,4],[1,3]]Output: 1Explanation: [1,3] can be removed and the rest of the intervals are non-overlapping. Example 2: 1234Input: intervals = [[1,2],[1,2],[1,2]]Output: 2Explanation: You need to remove two [1,2] to make the rest of the intervals non-overlapping. ...

ProblemThere is an integer array nums sorted in ascending order (with distinct values). Prior to being passed to your function, nums is possibly rotated at an unknown pivot index k (1 <= k < nums.length) such that the resulting array is [nums[k], nums[k+1], ..., nums[n-1], nums[0], nums[1], ..., nums[k-1]] (0-indexed). For example, [0,1,2,4,5,6,7] might be rotated at pivot index 3 and become [4,5,6,7,0,1,2]. Given the array nums after the possible rotation and an integer target, return the ...

ProblemThe thief has found himself a new place for his thievery again. There is only one entrance to this area, called root. Besides the root, each house has one and only one parent house. After a tour, the smart thief realized that all houses in this place form a binary tree. It will automatically contact the police if two directly-linked houses were broken into on the same night. Given the root of the binary tree, return the maximum amount of money the thief can rob without alerting the police ...

ProblemGiven an integer array nums, find the subarray with the largest sum, and return its sum . Example 1: 1234Input: nums = [-2,1,-3,4,-1,2,1,-5,4]Output: 6Explanation: The subarray [4,-1,2,1] has the largest sum 6. Example 2: 1234Input: nums = [1]Output: 1Explanation: The subarray [1] has the largest sum 1. Example 3: 1234Input: nums = [5,4,-1,7,8]Output: 23Explanation: The subarray [5,4,-1,7,8] has the largest sum 23. Constraints: 1 <= nums.length <= 10^5 10^4 <= nums[i] <= 1 ...

ProblemGiven an integer n, return the number of trailing zeroes in n!. Note that n! = n * (n - 1) * (n - 2) * ... * 3 * 2 * 1. Example 1: 1234Input: n = 3Output: 0Explanation: 3! = 6, no trailing zero. Example 2: 1234Input: n = 5Output: 1Explanation: 5! = 120, one trailing zero. Example 3: 123Input: n = 0Output: 0 Constraints: 0 <= n <= 10^4 Follow up: Could you write a solution that works in logarithmic time complexity? Solve這題先搞懂 trailing zeroes，是指尾巴的0 要計算尾巴有幾個0很簡單就是算其中乘了幾次(5*2) 由於每 ...

ProblemYou are given an m x n integer matrix matrix with the following two properties: Each row is sorted in non-decreasing order. The first integer of each row is greater than the last integer of the previous row. Given an integer target, return true if target is in matrix or false otherwise. You must write a solution in O(log(m * n)) time complexity. Example 1: !https://assets.leetcode.com/uploads/2020/10/05/mat.jpg 123Input: matrix = [[1,3,5,7],[10,11,16,20],[23,30,34,60]], target = 3Outpu ...

ProblemGiven a string s and a dictionary of strings wordDict, return true if s can be segmented into a space-separated sequence of one or more dictionary words. Note that the same word in the dictionary may be reused multiple times in the segmentation. Example 1: 1234Input: s = "leetcode", wordDict = ["leet","code"]Output: trueExplanation: Return true because "leetcode" can be segmented as "leet code". Example 2: 12345Input: s = "applepenap ...