Category: LEETCode

Suppose an array of length n sorted in ascending order is rotated between 1 and n times. For example, the array nums = [0,1,4,4,5,6,7] might become: Notice that rotating an array [a[0], a[1], a[2], …, a[n-1]] 1 time results in the array [a[n-1], a[0], a[1], a[2], …, a[n-2]]. Given the sorted rotated array nums that may contain duplicates, return the minimum element of this array. You must decrease the overall operation steps as much…

Read More “LeetCode Hard – Find Minimum in Rotated Sorted Array II” »

Given an array of points where points[i] = [xi, yi] represents a point on the X-Y plane, return the maximum number of points that lie on the same straight line. Example 1: Input: points = [[1,1],[2,2],[3,3]] Output: 3 Example 2: Input: points = [[1,1],[3,2],[5,3],[4,1],[2,3],[1,4]] Output: 4 Constraints: Java Solution To solve this problem, you can iterate through each pair of points and…

Read More “LeetCode Hard – Max Points on a Line” »

Given a string s and a dictionary of strings wordDict, add spaces in s to construct a sentence where each word is a valid dictionary word. Return all such possible sentences in any order. Note that the same word in the dictionary may be reused multiple times in the segmentation. Example 1: Input: s = “catsanddog”, wordDict = [“cat”,”cats”,”and”,”sand”,”dog”] Output: [“cats and…

Read More “LeetCode Hard – Word Break II” »

There are n children standing in a line. Each child is assigned a rating value given in the integer array ratings. You are giving candies to these children subjected to the following requirements: Return the minimum number of candies you need to have to distribute the candies to the children. Example 1: Input: ratings = [1,0,2] Output: 5 Explanation:…

Read More “LeetCode Hard –  Candy” »

Given a string s, partition s such that every  substring of the partition is a  palindrome. Return the minimum cuts needed for a palindrome partitioning of s. Example 1: Input: s = “aab” Output: 1 Explanation: The palindrome partitioning [“aa”,”b”] could be produced using 1 cut. Example 2: Input: s = “a” Output: 0 Example 3: Input: s = “ab” Output: 1 Constraints:…

Read More “LeetCode Hard – Palindrome Partitioning II” »

A transformation sequence from word beginWord to word endWord using a dictionary wordList is a sequence of words beginWord -> s1 -> s2 -> … -> sk such that: Given two words, beginWord and endWord, and a dictionary wordList, return the number of words in the shortest transformation sequence from beginWord to endWord, or 0 if no such sequence exists. Example 1: Input: beginWord = “hit”, endWord = “cog”, wordList = [“hot”,”dot”,”dog”,”lot”,”log”,”cog”] Output: 5 Explanation: One shortest transformation sequence…

Read More “LeetCode Hard – Word Ladder” »

A transformation sequence from word beginWord to word endWord using a dictionary wordList is a sequence of words beginWord -> s1 -> s2 -> … -> sk such that: Given two words, beginWord and endWord, and a dictionary wordList, return all the shortest transformation sequences from beginWord to endWord, or an empty list if no such sequence exists. Each sequence should be returned as a list of the words [beginWord, s1, s2, …, sk]. Example 1:…

Read More “LeetCode Hard – Word Ladder II” »

A path in a binary tree is a sequence of nodes where each pair of adjacent nodes in the sequence has an edge connecting them. A node can only appear in the sequence at most once. Note that the path does not need to pass through the root. The path sum of a path is the sum of the node’s…

Read More “LeetCode Hard – Binary Tree Maximum Path Sum” »

You are given an array prices where prices[i] is the price of a given stock on the ith day. Find the maximum profit you can achieve. You may complete at most two transactions. Note: You may not engage in multiple transactions simultaneously (i.e., you must sell the stock before you buy again). Example 1: Input: prices = [3,3,5,0,0,3,1,4] Output: 6 Explanation: Buy on…

Read More “LeetCode Hard – Best Time to Buy and Sell Stock III” »

Given two strings s and t, return the number of distinct subsequences of s which equals t. The test cases are generated so that the answer fits on a 32-bit signed integer. Example 1: Input: s = “rabbbit”, t = “rabbit” Output: 3 Explanation: As shown below, there are 3 ways you can generate “rabbit” from s. rabbbitrabbbitrabbbit Example 2: Input:…

Read More “LeetCode Hard – Distinct Subsequences” »