# Category: Software Development Engineer in Test

## Find three elements in an array that sum to a given value

Objec­tive:  Given an array of integer write an algorithm to find 3 elements that sum to a given number k. In short a+b+c = k. Example: int a [] = { 3,1,7,4,5,9,10} , k =...

## Majority Element- Boyer–Moore majority vote algorithm

Objec­tive:  Given an array of integer write an algorithm to find the majority element in it (if exist). Majority Element: If an element appears more than n/2 times in array where n is the size...

## Check whether the given number is a perfect square

Objec­tive:  Given an integer check whether it is a perfect square. Example: number = 37 Output: false number = 49 Output: true This is fun puzzle which is asked in the interview. Approach: Say number...

## Find the Index from which 0 starts

Objec­tive:  Given an array of integer which 1’s followed by 0’s. Find the starting index of 0. Example: int [] a = {1,1,1,1,1,1,1,1,1,1,0,0,0,0,0,0,0}; First Index from where 0 starts: 10 int [] a = {1,1,1}; ...

## Find the only element in array which appears only once

Objec­tive: Given an array of integers, all the elements are appear twice but one element which appears only once. Write an algorithm to find that element. Example: int [] a = { 1,5,6,2,1,6,4,3,2,5,3}; output:...

## Algorithm to calculate power(k,n).

Objective:  Given two numbers ‘k’ and ‘n’. Write an algorithm to calculate kn. Example: k = 4, n = 5 kn = 45 = 1024 k = 2, n = 3 kn = 23 =...

## Find the two repeating elements in a given array | 6 Approaches

Objective: Given an array of n+2 elements. All elements of the array are in range 1 to n and all elements occur once except two numbers which occur twice. Write an algorithm to find...

## Find two elements whose sum is closest to zero

Objective: Given an array of positive and negative integers, write a algorithm to find the two elements such their sum is closest to zero. Example: int a [] = {1, 4, -5, 3, -2,...

## Find duplicates in an given array in O(n) time and O(1) extra space.

Objective: Given an array of integers, find out duplicates in it. Example: int [] a = {4, 6, 2, 1, 2, 5}; Output: Array has duplicates : 2 int a [] = {1, 6,...

## Find the last non repeating character in a given string.

Objective: Given a string, write an algorithm to find the last non repeating character in it. Example: String input = “algorithms tutorials” Output: ‘u’ String input = “aabbccdd” Output: No repeating character found. Approach:...

## Find the last repeating character in a given string.

Objective: Given a string, write an algorithm to find the last repeating character in it. Example: String input = “horizon tutorials” Output: ‘i’ String input = “algorithms” Output: No repeating character found. Approach: Naive...

## Find the first non repeating character in a given string

Objective: Given a string, write an algorithm to find the first non repeating character in it. Example: String input = ” tutorial horizon” Output: ‘u’ String input = “aabbccadd” Output: No non-repeating character found....

## Find the first repeating character in a given string

Objective: Given a string, write an algorithm to find the first repeating character in it. Example: String input = “horizon tutorials” Output: ‘o’ String input = “algorithms” Output: No repeating character found. Approach: Naive...

## Print All Diagonals of a given matrix

Objective: Given two dimensional matrix, write an algorithm to print all the diagonals of matrix. Example: Approach: We will solve this problem in two parts. first half of diagonals and second half of diagonals....

## Kadane’s Algorithm – Maximum Subarray Problem

Objective:  The maximum subarray problem is the task of finding the contiguous subarray within a one-dimensional array of numbers which has the largest sum. Example: int [] A = {−2, 1, −3, 4, −1, 2, 1, −5,...