1048 Longest String Chain
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".
Note:
1 <= words.length <= 1000
1 <= words[i].length <= 16
words[i] only consists of English lowercase letters.
Clean Code
class Solution {
public:
static bool compare(const string &s1, const string &s2) {
return s1.length() < s2.length();
}
int longestStrChain(vector<string>& words) {
sort(words.begin(), words.end(), compare);
unordered_map<string, int> dp;
int res = 0;
for (string w : words) {
int best = 0;
for (int i = 0; i < w.length(); i++) {
string word = w.substr(0, i) + w.substr(i + 1);
best = max(best, dp[word] + 1);
}
dp[w] = best;
res = max(res, best);
}
return res;
}
}