# Tag: Memoized

## 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.

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## 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.

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## 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 not.

## 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.

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## Longest alternating subsequence

Longest Alternating Subsequence problem 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. In order words, find the length of longest subsequence with alternate low and high elements.

## Minimum Sum Partition problem

Given a set of positive integers S, partition the set S into two subsets S1, S2 such that the difference between the sum of elements in S1 and the sum of elements in S2 is minimized.

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## Subset sum problem

Given a set of positive integers and an integer s, is there any non-empty subset whose sum to s.

## 0-1 Knapsack problem

Given a set of items, each with a weight and a value, determine the number of each item to include in a collection so that the total weight is less than or equal to a given limit and the total value is as large as possible. Items are indivisible; you either take an item or …