 # Top Coding Interview Questions

• How do you reverse a given string in place? (solution)
• How do you print duplicate characters from a string? (solution)
• How do you check if two strings are anagrams of each other? (solution)
• How do you find all the permutations of a string? (solution)
• How can a given string be reversed using recursion? (solution)
• How do you check if a string contains only digits? (solution)
• How do you find duplicate characters in a given string? (solution)
• How do you count a number of vowels and consonants in a given string? (solution)
• How do you count the occurrence of a given character in a string? (solution)
• How do you print the first non-repeated character from a string? (solution)
• How do you convert a given String into int like the atoi()? (solution)
• How do you reverse words in a given sentence without using any library method? (solution)
• How do you check if two strings are a rotation of each other? (solution)
• How do you check if a given string is a palindrome? (solution)
• How do you find the length of the longest substring without repeating characters? (solution)
• Given string str, - How do you find the longest palindromic substring in str? (solution)
• How to convert a byte array to String? (solution)
• How to remove the duplicate character from String? (solution)
• How to find the maximum occurring character in given String? (solution)
• How do you remove a given character from String? (solution)

Most Common Solutions

``````// lot of things can be solvd by just gettig map of a string characters
const map ={};
const string = "Hello World";
const array = string.split("");
array.forEach(i => map[i] ? map[i] = map[i] + 1 : map[i] = 1);
console.log(map)``````
``````// lot of things can be solvd by just gettig map of a string characters
const string = "hello world";
const removeDups = [... new Set(string.split(""))].join("")``````
``````// Remove char from String
const removeChar = (string, char) {
return string.split("").filter(i => i !== char).join("");
}``````
• How to find the maximum occurring character in given String? (solution)
``````const getMaxChar = (string) => {
const map = {};
string.split("").forEach(char => {
map[char] = map[char] ? map[char] + 1 : 1;
});
max = 1;
char = string
for(let k in map){
if(map[k] > max) {
max = map[k];
char = k
}
}
return char;
}
console.log(getMaxChar("hello world"));``````
• How do you remove a given character from String? (solution)

``````const removeChar = (string, char) => {
return string.split("").filter(i => i !== char).join("")
}
console.log(removeChar("hello world",'h'));``````
``````How do you find the length of the longest substring without repeating characters?

```javascript
var lengthOfLongestSubstring = function(s) {
let count = 0;
let i = 0;
let j = 0;
let n = s.length;
let set = new Set();
while (i < n && j < n) {
let char = s.charAt(j);
if(!set.has(char)) {
j++;
count = Math.max (count, j - i);
} else {
set.delete(s.charAt(i));
i++;
}
}
return count;
};

let result = lengthOfLongestSubstring('abcabcbb')
console.log(result);``````
• How do you check if a given string is a palindrome
``````const mapOfString = str => {
const map ={};
str.split("").forEach(i => map[i] = map[i] ? map[i] + 1: 1);
return map;
}
const checkPalindrome = (string1, string2) => {
const mapObject1 = mapOfString(string1);
const mapObject2 = mapOfString(string2)
if(mapObject1.length !== mapObject2.length){
return false;
}
for(let i in mapObject1){
if(mapObject1[i] !== mapObject2[i]){
return false;
}
}
return true;
}
console.log(checkPalindrome("ffsss","sfsf"));``````
• How do you reverse a given string in place? (solution)

``"helloWorld".split("").reverse().join("");``
• How do you print duplicate characters from a string? (solution)
``````const mapOfString = str => {
const map ={};
str.split("").forEach(i => map[i] = map[i] ? map[i] + 1: 1);
return map;
}
const duplicateString = str => {
const arr =[];
const obj = mapOfString(str)
for(let j in obj){
if(obj[j] > 1){
arr.push(j)
}
}
return arr.join("")
}
console.log(duplicateString("wefdwd"));``````
• How do you find all the permutations of a string? (solution)

``````let findPermutations = (string) => {
if (!string || typeof string !== "string"){
} else if (string.length < 2 ){
return string
}

let permutationsArray = []

for (let i = 0; i < string.length; i++){
let char = string[i]

let remainingChars = string.slice(0, i) + string.slice(i + 1, string.length)

for (let permutation of findPermutations(remainingChars)){
permutationsArray.push(char + permutation) }
}
return permutationsArray
}``````
• How do you find the missing number in a given integer array of 1 to 100? (solution)
• How do you find the duplicate number on a given integer array? (solution)
• How do you find the largest and smallest number in an unsorted integer array? (solution)
• How do you find all pairs of an integer array whose sum is equal to a given number? (solution)
• How do you find duplicate numbers in an array if it contains multiple duplicates? (solution)
• How to remove duplicates from a given array in Java? (solution)
• How do you search a target value in a rotated array? (solution)
• Given an unsorted array of integers, find the length of the longest consecutive elements sequence? (solution)
• How is an integer array sorted in place using the quicksort algorithm? (solution)
• How do you remove duplicates from an array in place? (solution)
• How do you reverse an array in place in Java? (solution)
• How are duplicates removed from an array without using any library? (solution)
• How to convert a byte array to String? (solution)
• What is the difference between an array and a linked list? (answer)
• How do you perform a binary search in a given array? (solution)
• How to find a median of two sorts arrays? (solution)
• How to rotate an array left and right by a given number K? (solution)
• How do you find duplicates from an unsorted array? (solution)
• Given an array of integers sorted in ascending order, find the starting and ending position of a given value? (solution)
• Given an integer array, find the contiguous subarray (containing at least one number) which has the largest sum and return its sum? (solution)