LeetCode Maximum Erasure Value

You are given an array of positive integers nums and want to erase a subarray containing unique elements. The score you get by erasing the subarray is equal to the sum of its elements. Return the maximum score you can get by erasing exactly one subarray. An array b is called to be a subarray of a if it forms a contiguous subsequence of a, that is, if it is equal to a[l],a[l+1],…,a[r] for some (l,r). Example…… Continue reading LeetCode Maximum Erasure Value

Leetcode Integer to Roman Java Solution

Roman numerals are represented by seven different symbols: I, V, X, L, C, D and M. Symbol Value I 1 V 5 X 10 L 50 C 100 D 500 M 1000 For example, two is written as II in Roman numeral, just two one’s added together. Twelve is written as, XII, which is simply X + II. The number twenty seven is written as XXVII, which is XX + V + II. Roman numerals are…… Continue reading Leetcode Integer to Roman Java Solution

Leetcode Container With Most Water Java Solution

Given n non-negative integers a1, a2, …, an , where each represents a point at coordinate (i, ai). n vertical lines are drawn such that the two endpoints of line i is at (i, ai) and (i, 0). Find two lines, which together with x-axis forms a container, such that the container contains the most water. Note: You may not slant the container and n is at least 2. The…… Continue reading Leetcode Container With Most Water Java Solution

Leetcode Binary Tree Level Order Traversal II Java Solution

Given a binary tree, return the bottom-up level order traversal of its nodes’ values. (ie, from left to right, level by level from leaf to root). For example:Given binary tree [3,9,20,null,null,15,7], 3 / \ 9 20 / \ 15 7 return its bottom-up level order traversal as: [ [15,7], [9,20], [3] ] Solution:We can solve it multiple ways…… Continue reading Leetcode Binary Tree Level Order Traversal II Java Solution

Leetcode Unique Paths Java Solution

A robot is located at the top-left corner of a m x n grid (marked ‘Start’ in the diagram below). The robot can only move either down or right at any point in time. The robot is trying to reach the bottom-right corner of the grid (marked ‘Finish’ in the diagram below). How many possible unique paths are there?…… Continue reading Leetcode Unique Paths Java Solution

Leetcode Reconstruct Itinerary Java Solution

Given a list of airline tickets represented by pairs of departure and arrival airports [from, to], reconstruct the itinerary in order. All of the tickets belong to a man who departs from JFK. Thus, the itinerary must begin with JFK. Note: If there are multiple valid itineraries, you should return the itinerary that has the smallest lexical order…… Continue reading Leetcode Reconstruct Itinerary Java Solution

Leetcode Perfect Squares Java Solution

Given a positive integer n, find the least number of perfect square numbers (for example, 1, 4, 9, 16, …) which sum to n. Example 1: Input: n = 12 Output: 3 Explanation: 12 = 4 + 4 + 4. Example 2: Input: n = 13 Output: 2 Explanation: 13 = 4 + 9. Solution: We will solve…… Continue reading Leetcode Perfect Squares Java Solution

Leetcode Regular Expression Matching Java Solution

Given an input string (s) and a pattern (p), implement regular expression matching with support for ‘.’ and ‘*’. ‘.’ Matches any single character. ‘*’ Matches zero or more of the preceding element. The matching should cover the entire input string (not partial). Note: s could be empty and contains only lowercase letters a-z.p could be empty and contains only lowercase letters a-z, and…… Continue reading Leetcode Regular Expression Matching Java Solution

Leetcode ZigZag Conversion Java Solution

The string “PAYPALISHIRING” is written in a zigzag pattern on a given number of rows like this: (you may want to display this pattern in a fixed font for better legibility) P A H N A P L S I I G Y I R And then read line by line: “PAHNAPLSIIGYIR” Write the code that will take…… Continue reading Leetcode ZigZag Conversion Java Solution

Leetcode Sum Root to Leaf Numbers Java Solution

Given a binary tree containing digits from 0-9 only, each root-to-leaf path could represent a number. An example is the root-to-leaf path 1->2->3 which represents the number 123. Find the total sum of all root-to-leaf numbers. Note: A leaf is a node with no children. Example: Input: [1,2,3] 1 / \ 2 3 Output: 25 Explanation: The root-to-leaf path 1->2 represents…… Continue reading Leetcode Sum Root to Leaf Numbers Java Solution