My software development journey
Given an array A of distinct numbers, how to count the number of pairs (i,j) such that A[i] < A[j] For example, let us consider A = [2, 1, 3] the pairs are (1,2), (1,3), (2,3). So there are 3 pairs. Similarly for A = [10, 6, 9, 2], there are 6 pairs This problem…
Given an array [1, 2, 3,…N], we apply a series of reversal operations on different range of indices [L,R]. How to find out the position of a number after these operations are applied? For example consider an array of 5 numbers [1, 2, 3, 4, 5] and the number 2. Reverse elements between 1, and…
Given an array of numbers which contains all even numbers except one, or all add numbers except one. How do you find the different number? For example consider the array [1, 2, 3, 5, 9], 2 is the different number. Similarly in the array [10, 6, 7, 24, 36], 7 is the different number. This…
Given some amount N, and a set of denominations, how do you find the number of ways to make change for N? Let us assume that there is infinite supply of coins for each denomination. For example, if we have to make change for 4, and the given denominations are {1, 2, 3}, the possibilities…
Given two numbers A, B, What is the maximum value of A’ XOR B’, where A’, B’ are obtained by permuting the binary representations of A, B respectively. For example assume A = 3, B = 1 and they are represented in 4 bits. A = 0011, B = 0001 in binary. Suppose A’ =…
Given a number N, an array is created by first adding all the odd numbers, and then adding all the even numbers below N, How do we find the number at a given position K? For example consider N = 10, the array is [1, 3, 5, 7, 9, 2, 4, 6, 8, 10], the…
Given an array of numbers, how to find the maximum length of increasing (non-decreasing) continuous sub-sequence? For example consider the array [7, 9, 1, 3, 5, 8, 2], the maximum length is 4. Similarly for [23, 10, 18, 18, 6], it is 3. This is a straight forward implementation problem (appeared on Codeforces). Following is…
Given an array of numbers and a sum, how to check if there is any sub-array with the given sum. For example consider an array A = [7, 2, 9, 1, 5], and the sum is 12, then we can find a sub-array [2, 9, 1] which sums up to 12. So the answer is…
Given a number K, Find the shortest and smallest string which has K positions in it, such that the character at that position is alphabetically greater than the character immediately after it. Only the lower case alphabets [a-z] are allowed. For example consider K = 1 “ba” is the shortest and smallest string possible. There…
Given an array, how do we find the minimum difference between any two elements in that array? For example consider the array [56, 18, 89, 24, 10], the minimum difference is 6 (between 18, and 24). A straight forward method to find the minimum difference between any two pairs is to iterate through each possible…