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 Single Number II Java Solution

Given a non-empty array of integers, every element appears three times except for one, which appears exactly once. Find that single one. Note: Your algorithm should have a linear runtime complexity. Could you implement it without using extra memory? Example 1: Input: [2,2,3,2] Output: 3 Example 2: Input: [0,1,0,1,0,1,99] Output: 99 Solution 1: We will use a HashMap and…… Continue reading Leetcode Single Number II Java Solution

Leetcode Dungeon Game Java Solution

The demons had captured the princess (P) and imprisoned her in the bottom-right corner of a dungeon. The dungeon consists of M x N rooms laid out in a 2D grid. Our valiant knight (K) was initially positioned in the top-left room and must fight his way through the dungeon to rescue the princess. The…… Continue reading Leetcode Dungeon Game Java Solution

Leetcode 787 Cheapest Flights Within K Stops Java Solution

There are n cities connected by m flights. Each flight starts from city u and arrives at v with a price w. Now given all the cities and flights, together with starting city src and the destination dst, your task is to find the cheapest price from src to dst with up to k stops. If there is no…… Continue reading Leetcode 787 Cheapest Flights Within K Stops Java Solution

Leetcode 3 Longest Substring Without Repeating Characters

Given a string, find the length of the longest substring without repeating characters. Example 1: Input: “abcabcbb” Output: 3 Explanation: The answer is “abc”, with the length of 3. Example 2: Input: “bbbbb” Output: 1 Explanation: The answer is “b”, with the length of 1. Example 3: Input: “pwwkew” Output: 3 Explanation: The answer is “wke”, with…… Continue reading Leetcode 3 Longest Substring Without Repeating Characters

Leetcode 406 Queue Reconstruction by Height

Suppose you have a random list of people standing in a queue. Each person is described by a pair of integers (h, k), where h is the height of the person and k is the number of people in front of this person who have a height greater than or equal to h. Write an algorithm to reconstruct the queue. Note:The…… Continue reading Leetcode 406 Queue Reconstruction by Height

Leetcode 200 Number of Islands (Java) With Video Explanation

Given a 2d grid map of ‘1’s (land) and ‘0’s (water), count the number of islands. An island is surrounded by water and is formed by connecting adjacent lands horizontally or vertically. You may assume all four edges of the grid are all surrounded by water. Example : Input: 11000 11000 00100 00011 Output: 3 Solution: We…… Continue reading Leetcode 200 Number of Islands (Java) With Video Explanation

Leetcode 56 Merge Intervals (Java)

Given a collection of intervals, merge all overlapping intervals. Example 1: Input: [[1,3],[2,6],[8,10],[15,18]] Output: [[1,6],[8,10],[15,18]] Explanation: Since intervals [1,3] and [2,6] overlaps, merge them into [1,6]. Solution: We can solve this by comparing the start of the next interval with the end of the current interval and merged if the start of the next interval…… Continue reading Leetcode 56 Merge Intervals (Java)

Leetcode 23: Merge K Sorted Lists (Java)

Merge k sorted linked lists and return it as one sorted list. Analyze and describe its complexity. Example: Input: [   1->4->5,   1->3->4,   2->6 ] Output: 1->1->2->3->4->4->5->6 Solution: For this problem, the brute force solution would be passing all the lists and perform Merge Sort, but for the optimal solution we will use minHeap using…… Continue reading Leetcode 23: Merge K Sorted Lists (Java)