Zoho Coding Interview Questions

Climbing Stairs

You are climbing a staircase. It takes n steps to reach the top.

Spiral Matrix

Given an m x n matrix, return all elements of the matrix in spiral order.

Best Time to Buy and Sell Stock

You are given an array prices where prices[i] is the price of a given stock on the ith day.

Longest Palindromic Substring

Given a string s, return the longest palindromic substring in s.

Group Anagrams

Given an array of strings strs, group the anagrams together. You can return the answer in any order.

Longest Substring Without Repeating Characters

Given a string s, find the length of the longest substring without duplicate characters.

Decode String

Given an encoded string, return its decoded string.

Valid Parentheses

Given a string s containing just the characters '(', ')', '{', '}', '[' and ']', determine if the input string is valid.

Number of Islands

Given an m x n 2D binary grid grid which represents a map of '1's (land) and '0's (water), return the number of islands.

Move Zeroes

Given an integer array nums, move all 0's to the end of it while maintaining the relative order of the non-zero elements.

Trapping Rain Water

Given n non-negative integers representing an elevation map where the width of each bar is 1, compute how much water it can trap after raining.

Merge Intervals

Given an array of intervals where intervals[i] = [starti, endi], merge all overlapping intervals, and return an array of the non-overlapping intervals that cove...

Two Sum

Given an array of integers nums and an integer target, return the indices of the two numbers that add up to target.

Sort Even and Odd Indices Independently

You are given a 0-indexed integer array nums. Rearrange the values of nums according to the following rules:

Compare Version Numbers

Given two version strings, version1 and version2, compare them. A version string consists of revisions separated by dots '.'. The value of the revision is its i...

Rotate Image

You are given an n x n 2D matrix representing an image, rotate the image by 90 degrees (clockwise).

Largest Number

Given a list of non-negative integers nums, arrange them such that they form the largest number and return it.

Generate Parentheses

Given n pairs of parentheses, write a function to generate all combinations of well-formed parentheses.

Find Winner on a Tic Tac Toe Game

Tic-tac-toe is played by two players A and B on a 3 x 3 grid. The rules of Tic-Tac-Toe are:

Zigzag Conversion

The string "PAYPALISHIRING" is written in a zigzag pattern on a given number of rows like this: (you may want to display this pattern in a fixed font for better...

Rotate Array

Given an integer array nums, rotate the array to the right by k steps, where k is non-negative.

Excel Sheet Column Number

Given a string columnTitle that represents the column title as appears in an Excel sheet, return its corresponding column number.

Longest Common Prefix

Write a function to find the longest common prefix string amongst an array of strings.

Container With Most Water

You are given an integer array height of length n. There are n vertical lines drawn such that the two endpoints of the ith line are (i, 0) and (i, height[i]).

Remove All Occurrences of a Substring

Given two strings s and part, perform the following operation on s until all occurrences of the substring part are removed:

Regular Expression Matching

Given an input string s and a pattern p, implement regular expression matching with support for '.' and '' where:

Wildcard Matching

Given an input string (s) and a pattern (p), implement wildcard pattern matching with support for '?' and '' where:

Roman to Integer

Roman numerals are represented by seven different symbols: I, V, X, L, C, D and M.

Word Pattern

Given a pattern and a string s, find if s follows the same pattern.

Text Justification

Given an array of strings words and a width maxWidth, format the text such that each line has exactly maxWidth characters and is fully (left and right) justifie...

Median of Two Sorted Arrays

Given two sorted arrays nums1 and nums2 of size m and n respectively, return the median of the two sorted arrays.

Valid Sudoku

Determine if a 9 x 9 Sudoku board is valid. Only the filled cells need to be validated according to the following rules:

Basic Calculator II

Given a string s which represents an expression, evaluate this expression and return its value.

Replace Elements with Greatest Element on Right Side

Given an array arr, replace every element in that array with the greatest element among the elements to its right, and replace the last element with -1.

Non-overlapping Intervals

Given an array of intervals intervals where intervals[i] = [starti, endi], return the minimum number of intervals you need to remove to make the rest of the int...

Edit Distance

Given two strings word1 and word2, return the minimum number of operations required to convert word1 to word2.

Happy Number

Write an algorithm to determine if a number n is happy.

Longest Valid Parentheses

Given a string containing just the characters '(' and ')', return the length of the longest valid (well-formed) parentheses substring.

Merge Sorted Array

You are given two integer arrays nums1 and nums2, sorted in non-decreasing order, and two integers m and n, representing the number of elements in nums1 and num...

Product of Array Except Self

Given an integer array nums, return an array answer such that answer[i] is equal to the product of all the elements of nums except nums[i].

Count and Say

The count-and-say sequence is a sequence of digit strings defined by the recursive formula:

3Sum

Given an integer array nums, return all the triplets [nums[i], nums[j], nums[k]] such that i != j, i != k, and j != k, and nums[i] + nums[j] + nums[k] == 0.

Restore IP Addresses

A valid IP address consists of exactly four integers separated by single dots. Each integer is between 0 and 255 (inclusive) and cannot have leading zeros.

Search in Rotated Sorted Array

There is an integer array nums sorted in ascending order (with distinct values).

Find the Duplicate Number

Given an array of integers nums containing n + 1 integers where each integer is in the range [1, n] inclusive.

Decode Ways

You have intercepted a secret message encoded as a string of numbers. The message is decoded via the following mapping:

Jump Game

You are given an integer array nums. You are initially positioned at the array's first index, and each element in the array represents your maximum jump length...

Best Time to Buy and Sell Stock II

You are given an integer array prices where prices[i] is the price of a given stock on the ith day.

Letter Combinations of a Phone Number

Given a string containing digits from 2-9 inclusive, return all possible letter combinations that the number could represent. Return the answer in any order.

Sort Colors

Given an array nums with n objects colored red, white, or blue, sort them in-place so that objects of the same color are adjacent, with the colors in the order...

Combination Sum

Given an array of distinct integers candidates and a target integer target, return a list of all unique combinations of candidates where the chosen numbers sum...

Largest Rectangle in Histogram

Given an array of integers heights representing the histogram's bar height where the width of each bar is 1, return the area of the largest rectangle in the his...

Partition Equal Subset Sum

Given an integer array nums, return true if you can partition the array into two subsets such that the sum of the elements in both subsets is equal or false oth...

Maximum Subarray

Given an integer array nums, find the subarray with the largest sum, and return its sum.

Palindrome Number

Given an integer x, return true if x is a palindrome, and false otherwise.

Remove Duplicates from Sorted Array

Given an integer array nums sorted in non-decreasing order, remove the duplicates in-place such that each unique element appears only once. The relative order o...

Reverse Vowels of a String

Given a string s, reverse only all the vowels in the string and return it.

Find the Index of the First Occurrence in a String

Given two strings needle and haystack, return the index of the first occurrence of needle in haystack, or -1 if needle is not part of haystack.

3Sum Closest

Given an integer array nums of length n and an integer target, find three integers at distinct indices in nums such that the sum is closest to target.

Word Search

Given an m x n grid of characters board and a string word, return true if word exists in the grid.

Spiral Matrix II

Given a positive integer n, generate an n x n matrix filled with elements from 1 to n2 in spiral order.

N-Queens

The n-queens puzzle is the problem of placing n queens on an n x n chessboard such that no two queens attack each other.

Word Search II

Given an m x n board of characters and a list of strings words, return all words on the board.

Single Number

Given a non-empty array of integers nums, every element appears twice except for one. Find that single one.

Longest Consecutive Sequence

Given an unsorted array of integers nums, return the length of the longest consecutive elements sequence.

Integer to English Words

Convert a non-negative integer num to its English words representation.

Add to Array-Form of Integer

The array-form of an integer num is an array representing its digits in left to right order.

Diagonal Traverse

Given an m x n matrix mat, return an array of all the elements of the array in a diagonal order.

Merge Strings Alternately

You are given two strings word1 and word2. Merge the strings by adding letters in alternating order, starting with word1. If a string is longer than the other,...

Shuffle the Array

Given the array nums consisting of 2n elements in the form [x1,x2,...,xn,y1,y2,...,yn].

Word Break

Given a string s and a dictionary of strings wordDict, return true if s can be segmented into a space-separated sequence of one or more dictionary words.

Reverse Words in a String

Given an input string s, reverse the order of the words.

Integer to Roman

Seven different symbols represent Roman numerals with the following values:

Find Triangular Sum of an Array

You are given a 0-indexed integer array nums, where nums[i] is a digit between 0 and 9 (inclusive).

Maximum Population Year

You are given a 2D integer array logs where each logs[i] = [birthi, deathi] indicates the birth and death years of the ith person.

Find the Winner of the Circular Game

There are n friends that are playing a game. The friends are sitting in a circle and are numbered from 1 to n in clockwise order. More formally, moving clockwis...

Minimum Time Difference

Given a list of 24-hour clock time points in "HH:MM" format, return the minimum minutes difference between any two time-points in the list.

House Robber

You are a professional robber planning to rob houses along a street. Each house has a certain amount of money stashed, the only constraint stopping you from rob...

Coin Change

You are given an integer array coins representing coins of different denominations and an integer amount representing a total amount of money.

Permutations

Given an array nums of distinct integers, return all the possible permutations. You can return the answer in any order.

Search Insert Position

Given a sorted array of distinct integers and a target value, return the index if the target is found. If not, return the index where it would be if it were ins...

Longest Increasing Subsequence

Given an integer array nums, return the length of the longest strictly increasing subsequence.

Subsets

Given an integer array nums of unique elements, return all possible subsets (the power set).

Reverse Only Letters

Given a string s, reverse the string according to the following rules:

Asteroid Collision

We are given an array asteroids of integers representing asteroids in a row. The indices of the asteroid in the array represent their relative position in space...

Remove Duplicates from Sorted Array II

Given an integer array nums sorted in non-decreasing order, remove some duplicates in-place such that each unique element appears at most twice. The relative or...

Binary Search

Given an array of integers nums which is sorted in ascending order, and an integer target, write a function to search target in nums. If target exists, then ret...

Excel Sheet Column Title

Given an integer columnNumber, return its corresponding column title as it appears in an Excel sheet.

Isomorphic Strings

Given two strings s and t, determine if they are isomorphic.

Palindrome Linked List

Given the head of a singly linked list, return true if it is a palindrome or false otherwise.

Middle of the Linked List

Given the head of a singly linked list, return the middle node of the linked list.

Remove K Digits

Given string num representing a non-negative integer num, and an integer k, return the smallest possible integer after removing k digits from num.

Next Permutation

A permutation of an array of integers is an arrangement of its members into a sequence or linear order.

First Unique Character in a String

Given a string s, find the first non-repeating character in it and return its index. If it does not exist, return -1.

Cinema Seat Allocation

A cinema has n rows of seats, numbered from 1 to n and there are ten seats in each row, labelled from 1 to 10 as shown in the figure above.

Remove All Adjacent Duplicates In String

You are given a string s consisting of lowercase English letters. A duplicate removal consists of choosing two adjacent and equal letters and removing them.

The Latest Time to Catch a Bus

You are given a 0-indexed integer array buses of length n, where buses[i] represents the departure time of the ith bus. You are also given a 0-indexed integer a...

Maximum Sum of an Hourglass

You are given an m x n integer matrix grid.

Reverse Linked List II

Given the head of a singly linked list and two integers left and right where left <= right, reverse the nodes of the list from position left to position right,...

Unique Binary Search Trees

Given an integer n, return the number of structurally unique BST's (binary search trees) which has exactly n nodes of unique values from 1 to n.