Given a list of words, each word consists of English lowercase letters.
Let's say word1
is a predecessor of word2
if and only if we can add exactly one letter anywhere in word1
to make it equal to word2
. For example, "abc"
is a predecessor of "abac"
.
A word chain is a sequence of words [word_1, word_2, ..., word_k]
with k >= 1
, where word_1
is a predecessor of word_2
, word_2
is a predecessor of word_3
, and so on.
Return the longest possible length of a word chain with words chosen from the given list of words
.
Example 1:
Input: ["a","b","ba","bca","bda","bdca"] Output: 4 Explanation: one of the longest word chain is "a","ba","bda","bdca".
class Solution { public int longestStrChain(String[] words) { Arrays.sort(words, (a, b) -> a.length() - b.length()); // map is used as space for dp best[i] = 1 + best[i- 1] Map<String, Integer> map = new HashMap<>(); int res = 0; for (String word: words) { map.put(word, 1); for (int i = 0; i < word.length(); i++) { String prev = word.substring(0, i) + word.substring(i + 1); int curLen = map.get(word); if (map.containsKey(prev) && map.get(prev) + 1 > curLen) { map.put(word, map.get(prev) + 1); } } res = Math.max(res, map.get(word)); } return res; } }