#LeetCode : Power Of Two

Also Check: June LeetCoding Challenge (2020)

Given an integer, write a function to determine if it is a power of two.

Example 1:

Input: 1
Output: true 
Explanation: 20 = 1

#LeetCode : Coin Change 2

Also Check: June LeetCoding Challenge (2020)

You are given coins of different denominations and a total amount of money. Write a function to compute the number of combinations that make up that amount. You may assume that you have infinite number of each kind of coin.

Example 1:
Input: amount = 5, coins = [1, 2, 5]
Output: 4
Explanation: there are four ways to make up the amount:
5=5
5=2+2+1
5=2+1+1+1
5=1+1+1+1+1

#LeetCode :Queue Reconstruction by Height

Also Check: June LeetCoding Challenge (2020)

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 number of people is less than 1,100.

Example
Input:[[7,0], [4,4], [7,1], [5,0], [6,1], [5,2]]
Output:[[5,0], [7,0], [5,2], [6,1], [4,4], [7,1]]

#LeetCode : Reverse String

Also Check: June LeetCoding Challenge (2020)

Write a function that reverses a string. The input string is given as an array of characters char[].

Do not allocate extra space for another array, you must do this by modifying the input array in-place with O(1) extra memory.

You may assume all the characters consist of printable ascii characters.

#LeetCode : Two City Scheduling

Also Check: June LeetCoding Challenge (2020)

There are 2N people a company is planning to interview. The cost of flying the i-th person to city A is costs[i][0], and the cost of flying the i-th person to city B is costs[i][1].

Return the minimum cost to fly every person to a city such that exactly N people arrive in each city.

Example 1:
Input: [[10,20],[30,200],[400,50],[30,20]]
Output: 110
Explanation:
The first person goes to city A for a cost of 10.
The second person goes to city A for a cost of 30.
The third person goes to city B for a cost of 50.
The fourth person goes to city B for a cost of 20.

The total minimum cost is 10 + 30 + 50 + 20 = 110 to have half the people interviewing in each city.

#LeetCode Delete Node in a Linked List

Also Check: June LeetCoding Challenge (2020)

Write a function to delete a node (except the tail) in a singly linked list, given only access to that node.

Example 1:
Input: head = [4,5,1,9], node = 5
Output: [4,1,9]
Explanation: You are given the second node with value 5, the linked list should become 4 -> 1 -> 9 after calling your function.

#LeetCode: Invert Binary Tree

Also Check: June LeetCoding Challenge (2020)

Invert the given Binary tree

#LeetCode: Maximum consecutive one's

Also Check: LeetCode Solutions in Java

Let's say we want to find maximum consecutive one’s in a binary array.

Algorithm:
1). Maintain two counters current and max.
2). Start iterating the array, if 3.a). the current number is 1, we need to increment 'current'.
3). If the current number is 0, then we need perfom below checks:
3.a) If the 'current' is greater than 'max', we set 'current' in 'max'.
3.b). If max is greater than equal to half of array length, so we should return max as there is no point in checking the array further.
3.c). Set the 'current' as zero.
4). Return 'current' or 'max', which ever is higher.