Suppose we have a list of non-negative integers, a1, a2, ..., an, and another value, that is target, S. Now we have 2 symbols + and -. For each integer, we should choose one from + and - as its new symbol. we have to find out how many ways to assign symbols to make sum of integers same as the target value S. So if the numbers are [1, 1, 1, 1, 1], and S = 3, then the output will be 5, as the combinations are – 1 + 1 + 1 + 1 + 1 = 3, ... Read More

Suppose we have a string, we have to sort the characters based on the frequency. So if the string is like “abbbacbcc”, then the output will be “bbbbcccaa”To solve this, we will follow these steps −create an array of pairs called v, create one map mfor all characters in string, increase value of m[character] by 1i := first element of mapwhile map has elementsinsert (i.second, i.first) into vand increase i to point to the next elementsort the vector vans := an empty stringfor i := 0 to size of vt := first element of v[i]while t is not 0ans := ... Read More

Suppose we have an array of integers, in range 1 ≤ a[i] ≤ n (n = size of an array), here some elements appear twice and others appear once. We have to find all the elements that appear twice in this array. So if the array is [4, 3, 2, 7, 8, 2, 3, 1], then the output will be [2, 3]. Approach To solve this, we will follow these steps − n := size of array, make one array called ans for i in range 0 to n – 1 ... Read More

Suppose we have given a string s that consists of only uppercase letters, we can perform at most k operations on that string. In one operation, we can select any character of the string and change it to any other uppercase letters. We have to find the length of the longest sub-string containing all repeating letters we can get after performing the above operations. So if the input is like: “ABAB” and k = 2, then the output will be 4. This is because two ‘A’s with two ‘B’s or vice versa.To solve this, we will follow these steps −maxCount ... Read More

Suppose we have a non-empty string containing an out-of-order English representation of digits 0-9, output the digits in ascending order. There are some properties −Input is guaranteed to be valid and can be transformed to its original digits. That means invalid inputs such as "abc" or "zerone" are not permitted.Input length is less than 50, 000.So if the input is like “fviefuro”, then the output will be 45.To solve this, we will follow these steps −nums := an array that is holding the numbers in English letter from 0 to 9.make one array count of size 10ans := an empty ... Read More

Suppose we have a non-empty array containing only positive numbers, we have to find if the array can be partitioned into two subsets such that the sum of elements in both subsets is the same. So if the input is like [1, 5, 11, 5], the output will be true. As this array can be partitioned as [1, 5, 5] and [11]To solve this, we will follow these steps −n := size of the arraysum := 0for i := 0 to n – 1sum := sum + nums[i]if sum is odd, return falsesum := sum / 2create one array called ... Read More

Consider we have a random list of people standing in a queue. If each person is described by a pair of integers (h, k), where h is the height and k is the number of people in front of him, who have a height greater than or equal to h. We have to define one method to reconstruct the queue. So if the given array is like [[7, 0], [4, 4], [7, 1], [5, 0], [6, 1], [5, 2]], then the output will be [[5, 0], [7, 0], [5, 2], [6, 1], [4, 4], [7, 1]]To solve this, we will ... Read More

Suppose we have a string s, and we have to find the length of the longest substring T of that given string (consists of lowercase letters only) such that every character in T appears no less than k times. So if the string is “ababbc” and k = 2, then the output will be 3 and longest substring will be “ababb”, as there are two a’s and three b’s.To solve this, we will follow these steps −create one recursive function called longestSubstring(), this takes string s and size kif k = 1, then return the size of the stringif size ... Read More

Suppose we have an encoded string; we have to return its decoded string. The rule for encoding is: k[encoded_string], this indicates where the encoded_string inside the square brackets is being repeated exactly k times. We can assume that the original data does not contain any numeric characters and that digits are only for those repeat numbers, k. So if the input is like “1[ba]2[na]”, then the output will be “banana”.To solve this, we will follow these steps −create one empty stack, set i := 0while i < size of a stringif s[i] is ‘]’res := delete element from the stack ... Read More

Array transformation is a popular coding question asked in technical assessments and interviews. In this article, we will discuss the problem of array transformation with example testcases, the algorithm to solve it, and provide a C/C++ implementation. Array Transformation Based on Local Maxima and Minima In this problem, you are given an array of integers arr[] of size N. Every day the array undergoes a transformation which can be defined as follows: The first and last elements of the array are not transformed. For every other element arr[i] in the array, where 0 < i < N-1, ... Read More