Path In Zigzag Labelled Binary Tree

In an infinite binary tree where every node has two children, the nodes are labelled in row order. In the odd numbered rows (ie., the first, third, fifth,...), the labelling is left to right, while in the even numbered rows (second, fourth, sixth,...), the labelling is right to left. Given the label of a node in this … Continue reading Path In Zigzag Labelled Binary Tree

Merge k Sorted Lists

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 Java Program Implementation /** * Definition for singly-linked list. * public class ListNode { * int val; * ListNode next; * ListNode() {} * ListNode(int val) { … Continue reading Merge k Sorted Lists


Given an array nums of n integers, are there elements a, b, c in nums such that a + b + c = 0? Find all unique triplets in the array which gives the sum of zero. Note: The solution set must not contain duplicate triplets. Example: Given array nums = [-1, 0, 1, 2, -1, -4], A solution set is: [ [-1, 0, 1], [-1, -1, 2] ] Solution C# … Continue reading 3Sum

Climbing Stairs

You are climbing a stair case. It takes n steps to reach to the top. Each time you can either climb 1 or 2 steps. In how many distinct ways can you climb to the top? Note: Given n will be a positive integer. Example 1: Input: 2 Output: 2 Explanation: There are two ways to climb to the top. … Continue reading Climbing Stairs

Insert Interval

Given a set of non-overlapping intervals, insert a new interval into the intervals (merge if necessary). You may assume that the intervals were initially sorted according to their start times. Example 1: Input: intervals = [[1,3],[6,9]], newInterval = [2,5] Output: [[1,5],[6,9]] Example 2: Input: intervals = [[1,2],[3,5],[6,7],[8,10],[12,16]], newInterval = [4,8] Output: [[1,2],[3,10],[12,16]] Explanation: Because the new interval … Continue reading Insert Interval

Count Square Submatrices with All Ones

Given a m * n matrix of ones and zeros, return how many square submatrices have all ones. Example 1: Input: matrix = [   [0,1,1,1],   [1,1,1,1],   [0,1,1,1] ] Output: 15 Explanation: There are 10 squares of side 1. There are 4 squares of side 2. There is 1 square of side 3. Total number of squares … Continue reading Count Square Submatrices with All Ones

Insert Delete GetRandom O(1)

Hi Geeks! In this article, we going to see about how to insert, delete and get random elements with O(1) Time Complexity. Design a data structure that supports all following operations in average O(1) time. insert(val): Inserts an item val to the set if not already present.remove(val): Removes an item val from the set if present.getRandom: Returns a … Continue reading Insert Delete GetRandom O(1)

Longest Increasing Subsequence

Given an unsorted array of integers, find the length of longest increasing subsequence. Example: Input: [10,9,2,5,3,7,101,18] Output: 4 Explanation: The longest increasing subsequence is [2,3,7,101], therefore the length is 4. Note: There may be more than one LIS combination, it is only necessary for you to return the length.Your algorithm should run in O(n2) complexity. … Continue reading Longest Increasing Subsequence