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[0]
    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?

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)) {
            set.add(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"){
      return "Please enter a 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)

Top Coding Interview Questions String/Array

Top Coding Interview Questions

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