Category: Dynamic Programming

Count total possible combinations of N-digit numbers in a mobile keypad

Given a mobile keypad having digits from [0-9] associated with each key, count total possible combinations of digits having length n. We can start with any digit and press only four adjacent keys of any digit. Keypad also contains * and # key which we are not allowed to press. Get great deals at Amazon

Determine Minimal Adjustment Cost of an Array

Write an algorithm to replace each element in an array of positive integers such that the difference between adjacent elements in the array is less than or equal to a given target. We need to minimize the adjustment cost which is the sum of differences between new and old values. In other words, minimize ∑|A[i] …

Longest Common Subsequence of K-sequences

The longest common subsequence (LCS) problem is the problem of finding the longest subsequence that is present in given two sequences in the same order. i.e. find a longest sequence which can be obtained from the first original sequence by deleting some items, and from the second original sequence by deleting other items.

Wildcard Pattern Matching

Wildcard Pattern Matching: Given a string and a pattern containing wildcard characters i.e. ‘*’ and ‘?’, where ‘?’ can match to any single character in input string and ‘*’ can match to any number of characters including zero characters, design an efficient algorithm to find if the pattern matches with the complete input string or …

Longest Increasing Subsequence using LCS

The longest increasing subsequence problem is to find a subsequence of a given sequence in which the subsequence’s elements are in sorted order, lowest to highest, and in which the subsequence is as long as possible. This subsequence is not necessarily contiguous, or unique.  

Word Break Problem | Dynamic Programming

Word Break Problem: Given a string and a dictionary of words, determine if string can be segmented into a space-separated sequence of one or more dictionary words.

Find Optimal Cost to Construct Binary Search Tree

Find optimal cost to construct binary search tree where each key can repeat several times. We are given frequency of each key in same order as corresponding keys in inorder traversal of a binary search tree.

Longest Alternating Subsequence Problem

Longest Alternating Subsequence is a problem of finding a subsequence of a given sequence in which the elements are in alternating order, and in which the sequence is as long as possible.