tcs Coding Interview Questions

Two Sum

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

Palindrome Number

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

Majority Element

Given an array nums of size n, return the majority element.

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.

Maximum Subarray

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

Longest Common Prefix

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

Valid Parentheses

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

Rotate Array

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

Fibonacci Number

The Fibonacci numbers, commonly denoted F(n) form a sequence, called the Fibonacci sequence, such that each number is the sum of the two preceding ones, startin...

Subarray Sum Equals K

Given an array of integers nums and an integer k, return the total number of subarrays whose sum equals to k.

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.

Reverse Integer

Given a signed 32-bit integer x, return x with its digits reversed. If reversing x causes the value to go outside the signed 32-bit integer range [-231, 231 - 1...

Maximum Ascending Subarray Sum

Given an array of positive integers nums, return the maximum possible sum of an strictly increasing subarray in nums.

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...

Count the Digits That Divide a Number

Given an integer num, return the number of digits in num that divide num.

Palindrome Partitioning IV

Given a string s, return true if it is possible to split the string s into three non-empty palindromic substrings. Otherwise, return false.​​​​​

Remove Letter To Equalize Frequency

You are given a 0-indexed string word, consisting of lowercase English letters. You need to select one index and remove the letter at that index from word so th...

Minimum Cuts to Divide a Circle

A valid cut in a circle can be:

Minimum Operations to Exceed Threshold Value I

You are given a 0-indexed integer array nums, and an integer k.

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...

Minimum Operations to Exceed Threshold Value II

You are given a 0-indexed integer array nums, and an integer k.

Valid Anagram

Given two strings s and t, return true if t is an anagram of s, and false otherwise.

Single Number

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

Unique Paths

There is a robot on an m x n grid. The robot is initially located at the top-left corner (i.e., grid[0][0]). The robot tries to move to the bottom-right corner...

Roman to Integer

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

Bitwise ORs of Subarrays

Given an integer array arr, return the number of distinct bitwise ORs of all the non-empty subarrays of arr.

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.

Climbing Stairs

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

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.

Longest Palindromic Substring

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

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...

Second Highest Salary

Table: Employee

Plus One

You are given a large integer represented as an integer array digits, where each digits[i] is the ith digit of the integer. The digits are ordered from most sig...

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]).

Pow(x, n)

Implement pow(x, n), which calculates x raised to the power n (i.e., xn).

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...

Length of Last Word

Given a string s consisting of words and spaces, return the length of the last word in the string.

Happy Number

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

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.

Missing Number

Given an array nums containing n distinct numbers in the range [0, n], return the only number in the range that is missing from the array.

Reverse Words in a String

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

Contains Duplicate

Given an integer array nums, return true if any value appears at least twice in the array, and return false if every element is distinct.

Sliding Window Maximum

You are given an array of integers nums, there is a sliding window of size k which is moving from the very left of the array to the very right. You can only see...

Spiral Matrix

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

Toeplitz Matrix

Given an m x n matrix, return true if the matrix is Toeplitz. Otherwise, return false.

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.

Sqrt(x)

Given a non-negative integer x, return the square root of x rounded down to the nearest integer. The returned integer should be non-negative as well.

Merge Two Sorted Lists

You are given the heads of two sorted linked lists list1 and list2.

Set Matrix Zeroes

Given an m x n integer matrix matrix, if an element is 0, set its entire row and column to 0's.

Max Consecutive Ones III

Given a binary array nums and an integer k, return the maximum number of consecutive 1's in the array if you can flip at most k 0's.

Check if Array Is Sorted and Rotated

Given an array nums, return true if the array was originally sorted in non-decreasing order, then rotated some number of positions (including zero). Otherwise,...

Longest Substring Without Repeating Characters

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

Add Two Numbers

You are given two non-empty linked lists representing two non-negative integers. The digits are stored in reverse order, and each of their nodes contains a sing...

Department Top Three Salaries

Table: Employee

Generate Parentheses

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

N-th Tribonacci Number

The Tribonacci sequence Tn is defined as follows:

Single Element in a Sorted Array

You are given a sorted array consisting of only integers where every element appears exactly twice, except for one element which appears exactly once.

Add Binary

Given two binary strings a and b, return their sum as a binary string.

4Sum

Given an array nums of n integers, return an array of all the unique quadruplets [nums[a], nums[b], nums[c], nums[d]] such that:

Article Views I

Table: Views

Find Customer Referee

Table: Customer

K-diff Pairs in an Array

Given an array of integers nums and an integer k, return the number of unique k-diff pairs in the array.

Reverse Linked List

Given the head of a singly linked list, reverse the list, and return the reversed list.

Fizz Buzz

Given an integer n, return a string array answer (1-indexed) where:

Reverse String

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

Same Tree

Given the roots of two binary trees p and q, write a function to check if they are the same or not.

Largest Number

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

Find First and Last Position of Element in Sorted Array

Given an array of integers nums sorted in non-decreasing order, find the starting and ending position of a given target value.

Next Permutation

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

Pascal's Triangle

Given an integer numRows, return the first numRows of Pascal's triangle.

Sort Array by Increasing Frequency

Given an array of integers nums, sort the array in increasing order based on the frequency of the values. If multiple values have the same frequency, sort them...

Edit Distance

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

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...

Longest Common Subsequence

Given two strings text1 and text2, return the length of their longest common subsequence. If there is no common subsequence, return 0.

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...

Subsets

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

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...

Rotate String

Given two strings s and goal, return true if and only if s can become goal after some number of shifts on s.

Longest Consecutive Sequence

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

Maximum Product Subarray

Given an integer array nums, find a subarray that has the largest product, and return the product.

Employee Bonus

Table: Employee

Sort Characters By Frequency

Given a string s, sort it in decreasing order based on the frequency of the characters. The frequency of a character is the number of times it appears in the st...

Power of Two

Given an integer n, return true if it is a power of two. Otherwise, return false.

Search a 2D Matrix II

Write an efficient algorithm that searches for a value target in an m x n integer matrix matrix. This matrix has the following properties:

Sum of Unique Elements

You are given an integer array nums. The unique elements of an array are the elements that appear exactly once in the array.

Number of Employees Who Met the Target

There are n employees in a company, numbered from 0 to n - 1. Each employee i has worked for hours[i] hours in the company.

Big Countries

Table: World

Path with Maximum Probability

You are given an undirected weighted graph of n nodes (0-indexed), represented by an edge list where edges[i] = [a, b] is an undirected edge connecting the node...

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...

Word Search

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

Partition List

Given the head of a linked list and a value x, partition it such that all nodes less than x come before nodes greater than or equal to x.

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.

How Many Numbers Are Smaller Than the Current Number

Given the array nums, for each nums[i] find out how many numbers in the array are smaller than it. That is, for each nums[i] you have to count the number of val...

Peak Index in a Mountain Array

You are given an integer mountain array arr of length n where the values increase to a peak element and then decrease.

Count Primes

Given an integer n, return the number of prime numbers that are strictly less than n.

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].

Coin Change

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

Students and Examinations

Table: Students

Intersection of Two Arrays

Given two integer arrays nums1 and nums2, return an array of their intersection. Each element in the result must be unique and you may return the result in any...

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.