1048. Longest String Chain | LeetCode Solution

 1048. Longest String Chain | LeetCode Solution

You are given an array of words where each word consists of lowercase English letters.

wordA is a predecessor of wordB if and only if we can insert exactly one letter anywhere in wordA without changing the order of the other characters to make it equal to wordB.

  • For example, "abc" is a predecessor of "abac", while "cba" is not a predecessor of "bcad".

word chain is a sequence of words [word1, word2, ..., wordk] with k >= 1, where word1 is a predecessor of word2word2 is a predecessor of word3, and so on. A single word is trivially a word chain with k == 1.

Return the length of the longest possible word chain with words chosen from the given list of words.


Example 1:

Input: words = ["a","b","ba","bca","bda","bdca"]
Output: 4
Explanation: One of the longest word chains is ["a","ba","bda","bdca"].

Example 2:

Input: words = ["xbc","pcxbcf","xb","cxbc","pcxbc"]
Output: 5
Explanation: All the words can be put in a word chain ["xb", "xbc", "cxbc", "pcxbc", "pcxbcf"].

Example 3:

Input: words = ["abcd","dbqca"]
Output: 1
Explanation: The trivial word chain ["abcd"] is one of the longest word chains.
["abcd","dbqca"] is not a valid word chain because the ordering of the letters is changed.



  • 1 <= words.length <= 1000
  • 1 <= words[i].length <= 16
  • words[i] only consists of lowercase English letters.

class Solution
  static bool cmp(string a, string b)
    return a.length() < b.length();

  int longestStrChain(vector<string> &v)
    map<string, int> m;
    int ans = 1;
    sort(v.begin(), v.end(), cmp);
    for (int i = 0; i < v.size(); i++)
      string s = v[i];
      int maxx = 0;
      for (int j = 0; j < s.length(); j++)
        string temp = s;
        temp.erase(temp.begin() + j);
        maxx = max(maxx, m[temp]);
      m[s] = maxx + 1;
      ans = max(ans, m[s]);
    return ans;

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