- Trending Categories
- Data Structure
- Networking
- RDBMS
- Operating System
- Java
- iOS
- HTML
- CSS
- Android
- Python
- C Programming
- C++
- C#
- MongoDB
- MySQL
- Javascript
- PHP

- Selected Reading
- UPSC IAS Exams Notes
- Developer's Best Practices
- Questions and Answers
- Effective Resume Writing
- HR Interview Questions
- Computer Glossary
- Who is Who

# Program to find length longest prefix sequence of a word array in Python

Suppose we have a list of words called w, with lowercase strings. We have to find the length of the longest sequence of w where each previous word is the prefix of the next word and the next word has just one new character appended.

So, if the input is like w = ["pqr", "pq", "m", "mn", "pqrs"], then the output will be 3 because we can get the sequence: ["pq", "pqr", "pqrs"], whose length is 3.

To solve this, we will follow these steps −

- sort the list w
- dp := a map, where default value for a key is 0
- res := 0
- for each word in w, do
- dp[word] := dp[substring of word up to second last element] + 1
- res := maximum of res and dp[word]

- return res

## Example

Let us see the following implementation to get better understanding −

from collections import defaultdict def solve(w): w.sort() dp = defaultdict(int) res = 0 for word in w: dp[word] = dp[word[:-1]] + 1 res = max(res, dp[word]) return res w = ["pqr", "pq", "m", "mn", "pqrs"] print(solve(w))

## Input

["pqr", "pq", "m", "mn", "pqrs"]

## Output

3

- Related Questions & Answers
- Program to find length of longest consecutive sequence in Python
- Program to find length of longest diminishing word chain in Python?
- C++ Program to Find the Longest Prefix Matching of a Given Sequence
- Program to find length of longest matrix path length in Python
- C++ program for length of the longest word in a sentence
- Program to find length of longest word that can be formed from given letters in python
- Program to find longest common prefix from list of strings in Python
- Program to find length of longest possible stick in Python?
- Program to find length of longest balanced subsequence in Python
- Program to find length of longest anagram subsequence in Python
- Program to find length of longest distinct sublist in Python
- Program to find length of longest increasing subsequence in Python
- Program to find length of longest palindromic substring in Python
- Program to find length of longest palindromic subsequence in Python
- Program to find length of longest fibonacci subsequence in Python

Advertisements