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LeetCode solutions

1129. Longest String Chain

My accepted Python solution to LeetCode problem 1129, Longest String Chain, running in 47ms.

  • Difficulty: Medium
  • Python
  • Runtime 47ms
  • Memory 17.5MB

Read the problem on LeetCode View on GitHub

The problem statement is LeetCode’s and stays on their site. What follows is my accepted solution.

Python

Accepted on LeetCode — runtime 47ms, memory 17.5MB, accepted 2026-01-02.

python
class Solution:
    def longestStrChain(self, words: List[str]) -> int:
        # Sort by length
        words.sort(key=len)
        
        # dp[word] = longest chain ending at word
        dp = {}
        max_len = 1
        
        for word in words:
            dp[word] = 1
            
            # Try removing each character
            for i in range(len(word)):
                predecessor = word[:i] + word[i+1:]
                if predecessor in dp:
                    dp[word] = max(dp[word], dp[predecessor] + 1)
            
            max_len = max(max_len, dp[word])
        
        return max_len

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