How to find all duplicates in an array without using extra space?
Given an array of integers, the integers are in the range of 1 ≤ a[i] ≤ n (n = size of array). In this Array, some elements appear twice and others appear once.
Find all the elements that appear twice in this array.
We have to solve this problem without using extra space and in O(n) time complexity.
For Example:
Input: [4, 3, 2, 7, 8, 2, 3, 1]
Output: [2, 3]
Valid palindrome.
Given an input string. We have to write a code to check if it is a palindrome, considering only alphanumeric characters and ignoring cases.
Note: For this problem, consider the empty string as a valid palindrome.
For Example –
Example 1:
Input: “A man, a plan, a canal: Panama”
Output: true
Explanation: After removing non-alphanumeric characters, the string is amanaplanacanalpanama. So, it’s a palindrome
Example 2:
Input: “race a car”
Output: false
Given a binary Tree, write a code to return binary tree zigzag level order traversal of its node’s values. (ie, from left to right, then right to left for the next level and alternate between).
In the screenshot below, We have printed the zigzag traversal of a binary tree. We have printed the values from left to right for the first level. For the second level, we then moved from right to left. Then for the next level, we move from left to right and so on.