[leetcode]820. Short Encoding of Words

Analysis

好冷鴨—— [每天刷題並不難0.0]

Given a list of words, we may encode it by writing a reference string S and a list of indexes A.
For example, if the list of words is [“time”, “me”, “bell”], we can write it as S = “time#bell#” and indexes = [0, 2, 5].
Then for each index, we will recover the word by reading from the reference string from that index until we reach a “#” character.
What is the length of the shortest reference string S possible that encodes the given words?

Implement

class Solution {
public:
    int minimumLengthEncoding(vector<string>& words) {
        int len = words.size();
        for(int i=0; i<len; i++)
            reverse(words[i].begin(), words[i].end());
        sort(
 
words.begin(), words.end());
        vector<string> words1;
        words1.push_back(words[len-1]);
        string tmp = words[len-1];
        for(int i=len-2; i>=0; i--){
            if(tmp.find(words[i]) == string::npos){
                tmp = words[i];
                words1.push_back(tmp)
 
;
            }
        }
        int res = 0;
        for(auto word:words1)
            res += word.size();
        res += words1.size();
        return res;
    }
};

下面是大神的巧妙做法，就是先把整個輸入存在hash表中，然後刪掉所有字首，最後剩下的就是shortcode

class Solution {
public:
    int minimumLengthEncoding(vector<string>& words) {
        unordered_set<string> w(words.begin(), words.end());
        for(string word:w){
            for(int i=1; i<word.size(); i++)
                w.erase(word.substr(i));
        }
        int res = 0;
        for(string word:w)
            res += word.size()+1;
        return res;
    }
};