Find Common Elements in Three Sorted Arrays – Java Code

Write a java program to find common elements in three sorted arrays. Given three sorted arrays, write a code to print intersection of three sorted arrays.

For example –

arr1 = {1, 5, 10, 20, 40, 80};
arr2 = {6, 7, 20, 80, 100};
arr3 = {3, 4, 15, 20, 30, 70, 80, 120};

Output : {20, 80}

20 and 80 is the common element between three sorted arrays.

Get Minimum Element from Stack in O(1)

Design a stack in which we get minimum element from stack in O(1) (constant time).

For example : Suppose i push following elements in a stack.

9  ==> Top
1
2
3

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Then if i call getMin(), It will return 1 in O(1). In a stack, Element which pushed last in the stack is the first element to be popped out. Think for a moment how we can solve this problem.

How to Check if a Number is a Power of 2

How to check if a number is a power of 2.  To understand this question, let’s take some example.

Example –

Input – 16   – 16 is a power of 2 (2^4).

Input – 15 – 15 is not a power of 2.

Input – 32- 32 is a power of 2 (2^5).

We can use multiple approaches to check whether a number is a power of 2 or not.

Find GCD of Two Numbers using Recursion – Java Code

Write a Java program to find GCD of two numbers using Recursion. Given two input integers, we have to write a code to find GCD of two numbers using recursion. For this program, I assume you are familiar with the concept of recursion. If you don’t know about recursion then check my previous post on recursion vs iteration.

Find First Non-repeated Character in a String – Java Code

Write a java program to find first non-repeated character in a string. Given an input string, Write a java code to find first non-repeated character in a string.

For example –

i) Input string – java
Output – j (j is the first non-repeating character in a string)

ii) Input string – web rewrite
Output – b (b is the first non-repeating character in a string)

PHP Code to Find Second Largest Number in Array

Write a PHP code to find second largest number in array. Given an unsorted array, we have to write a PHP program to find the second largest number in an array.

Apart from solving this problem. We have to focus on time complexity. As the time complexity of an algorithm is very important in terms of an interview.