How to Crack Coding Interviews Archives

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 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 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