#LeetCode: Edit Distance

Also Check: Solutions Of May LeetCoding Challenge (2020)

Given two words word1 and word2, find the minimum number of operations required to convert word1 to word2.

You have the following 3 operations permitted on a word:

• Insert a character
• Delete a character
• Replace a character

#LeetCode: K Closest Points to Origin

Also Check: Solutions Of May LeetCoding Challenge (2020)

We have a list of points on the plane.  Find the K closest points to the origin (0, 0).(Here, the distance between two points on a plane is the Euclidean distance.)

You may return the answer in any order.  The answer is guaranteed to be unique (except for the order that it is in.)

#LeetCode: Course Schedule

Also Check: Solutions Of May LeetCoding Challenge (2020)

There are a total of numCourses courses you have to take, labeled from 0 to numCourses-1.

Some courses may have prerequisites, for example to take course 0 you have to first take course 1, which is expressed as a pair: [0,1]

Given the total number of courses and a list of prerequisite pairs, is it possible for you to finish all courses?

Example 1:
Input: numCourses = 2, prerequisites = [[1,0]]
Output: true
Explanation: There are a total of 2 courses to take.
             To take course 1 you should have finished course 0. So it is possible.

Example 2:
Input: numCourses = 2, prerequisites = [[1,0],[0,1]]
Output: false
Explanation: There are a total of 2 courses to take.
             To take course 1 you should have finished course 0, and to take course 0 you should
             also have finished course 1. So it is impossible.

Constraints:
The input prerequisites is a graph represented by a list of edges, not adjacency matrices. Read more about how a graph is represented.
You may assume that there are no duplicate edges in the input prerequisites.
1 <= numCourses <= 10^5

GIT URL: Java Solution of Leet Code's Course Schedule problem

Java Solution 1

ALSO CHECK: Other LeetCode Solutions in Java

-K Himaanshu Shuklaa.

#LeetCode: Counting Bits

Also Check: Solutions Of May LeetCoding Challenge (2020)

Given a non negative integer number num. For every numbers i in the range 0 ≤ i ≤ num calculate the number of 1's in their binary representation and return them as an array.

Example 1:
Input: 2
Output: [0,1,1]

Example 2:
Input: 5
Output: [0,1,1,2,1,2]

#LeetCode: Possible Bipartition

Also Check: Solutions Of May LeetCoding Challenge (2020)

Given a set of N people (numbered 1, 2, ..., N), we would like to split everyone into two groups of any size.

Each person may dislike some other people, and they should not go into the same group.

Formally, if dislikes[i] = [a, b], it means it is not allowed to put the people numbered a and b into the same group.

Return true if and only if it is possible to split everyone into two groups in this way.

#LeetCode: Contiguous Array

Also Check: Solutions Of May LeetCoding Challenge (2020)

Given a binary array, find the maximum length of a contiguous subarray with equal number of 0 and 1.

Example 1: Input: [0,1], Output: 2
Explanation: [0, 1] is the longest contiguous subarray with equal number of 0 and 1.

Example 2: Input: [0,1,0], Output: 2
Explanation: [0, 1] (or [1, 0]) is a longest contiguous subarray with equal number of 0 and 1.

Note: The length of the given binary array will not exceed 50,000.

#LeetCode: Uncrossed Lines

Also Check: Solutions Of May LeetCoding Challenge (2020)

We write the integers of A and B (in the order they are given) on two separate horizontal lines.

Now, we may draw connecting lines: a straight line connecting two numbers A[i] and B[j] such that:
A[i] == B[j];
The line we draw does not intersect any other connecting (non-horizontal) line.
Note that a connecting lines cannot intersect even at the endpoints: each number can only belong to one connecting line.

Return the maximum number of connecting lines we can draw in this way.

#LeetCode: Construct Binary Search Tree from Preorder Traversal

Also Check: Solutions Of May LeetCoding Challenge (2020)

Return the root node of a binary search tree that matches the given preorder traversal.

(Recall that a binary search tree is a binary tree where for every node, any descendant of node.left has a value < node.val, and any descendant of node.right has a value > node.val.  Also recall that a preorder traversal displays the value of the node first, then traverses node.left, then traverses node.right.)

It's guaranteed that for the given test cases there is always possible to find a binary search tree with the given requirements.

#LeetCode: Interval List Intersections

Also Check: Solutions Of May LeetCoding Challenge (2020)

Given two lists of closed intervals, each list of intervals is pairwise disjoint and in sorted order.

Return the intersection of these two interval lists.

(Formally, a closed interval [a, b] (with a <= b) denotes the set of real numbers x with a <= x <= b.  The intersection of two closed intervals is a set of real numbers that is either empty, or can be represented as a closed interval.  For example, the intersection of [1, 3] and [2, 4] is [2, 3].)

#LeetCode: Sort Characters By Frequency

Also Check: Solutions Of May LeetCoding Challenge (2020)

Given a string, sort it in decreasing order based on the frequency of characters.

Example 1:
Input: "tree"
Output: "eert"
Explanation:
'e' appears twice while 'r' and 't' both appear once.
So 'e' must appear before both 'r' and 't'. Therefore "eetr" is also a valid answer.

#LeetCode: Count Square Submatrices with All Ones

Also Check: Solutions Of May LeetCoding Challenge (2020)

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 = 10 + 4 + 1 = 15.

#LeetCode: Kth Smallest Element in a BST

Also Check: Solutions Of May LeetCoding Challenge (2020)

Given a binary search tree, write a function kthSmallest to find the kth smallest element in it.

Note:
You may assume k is always valid, 1 ≤ k ≤ BST's total elements.

Example 1:
Input: root = [3,1,4,null,2], k = 1
   3
  / \
 1   4
  \
   2
Output: 1
Example 2:
Input: root = [5,3,6,2,4,null,null,1], k = 3
       5
      / \
     3   6
    / \
   2   4
  /
 1
Output: 3

#LeetCode: Online Stock Span

Also Check: Solutions Of May LeetCoding Challenge (2020)

Write a class StockSpanner which collects daily price quotes for some stock, and returns the span of that stock's price for the current day.

The span of the stock's price today is defined as the maximum number of consecutive days (starting from today and going backwards) for which the price of the stock was less than or equal to today's price.

For example, if the price of a stock over the next 7 days were [100, 80, 60, 70, 60, 75, 85], then the stock spans would be [1, 1, 1, 2, 1, 4, 6].

#LeetCode: Permutation in String

Also Check: Solutions Of May LeetCoding Challenge (2020)

Given two strings s1 and s2, write a function to return true if s2 contains the permutation of s1. In other words, one of the first string's permutations is the substring of the second string.

Example 1:
Input: s1 = "ab" s2 = "eidbaooo"
Output: True
Explanation: s2 contains one permutation of s1 ("ba").

Example 2:
Input:s1= "ab" s2 = "eidboaoo"
Output: False

#LeetCode: Find All Anagrams in a String

Also Check: Solutions Of May LeetCoding Challenge (2020)

Given a string s and a non-empty string p, find all the start indices of p's anagrams in s.

Strings consists of lowercase English letters only and the length of both strings s and p will not be larger than 20,100.

The order of output does not matter.

#LeetCode: Odd Even Linked List

Also Check: Solutions Of May LeetCoding Challenge (2020)

Given a singly linked list, group all odd nodes together followed by the even nodes. Please note here we are talking about the node number and not the value in the nodes.

You should try to do it in place. The program should run in O(1) space complexity and O(nodes) time complexity.

#LeetCode: Maximum Sum Circular Subarray

Also Check: Solutions Of May LeetCoding Challenge (2020)

Given a circular array C of integers represented by A, find the maximum possible sum of a non-empty subarray of C.

Here, a circular array means the end of the array connects to the beginning of the array.  (Formally, C[i] = A[i] when 0 < = i  < A.length, and C[i+A.length] = C[i] when i > = 0.)

Also, a subarray may only include each element of the fixed buffer A at most once.  (Formally, for a subarray C[i], C[i+1], ..., C[j], there does not exist i < = k1, k2 < = j with k1 % A.length = k2 % A.length.)

Example 1:
Input: [1,-2,3,-2]
Output: 3
Explanation: Subarray [3] has maximum sum 3

#LeetCode: Implement Trie (Prefix Tree)

Also Check: Solutions Of May LeetCoding Challenge (2020)

Implement a trie with insert, search, and startsWith methods.

Example:
Trie trie = new Trie();
trie.insert("apple");
trie.search("apple");   // returns true
trie.search("app");     // returns false
trie.startsWith("app"); // returns true
trie.insert("app"); 
trie.search("app");     // returns true

Note:
You may assume that all inputs are consist of lowercase letters a-z.
All inputs are guaranteed to be non-empty strings.

#LeetCode: Remove K Digits

Also Check: Solutions Of May LeetCoding Challenge (2020)

Given a non-negative integer number represented as a string, remove k digits from the number so that the new number is the smallest possible.

#LeetCode:Single Element in a Sorted Array

Also Check: Solutions Of May LeetCoding Challenge (2020)

You are given a sorted array consisting of only integers where every element appears exactly twice, except for one element which appears exactly once. Find this single element that appears only once.

Example 1:
Input: [1,1,2,3,3,4,4,8,8]
Output: 2

Example 2:
Input: [3,3,7,7,10,11,11]
Output: 10