LeetCode -- 916. 单词子集

 本题，我们可以先统计出words2中所有单词中每个字母出现的最大频次；再和words1中的每个单词依次进行比较。

python
class Solution:
    def wordSubsets(self, words1: List[str], words2: List[str]) -> List[str]:
        cnt = Counter()
        for it in words2:
            ct = Counter(it)
            for it2 in ct:
                cnt[it2] = max(cnt[it2], ct[it2])
        res = []

        for wd in words1:
            ct = Counter(wd)
            flag = True
            for it2 in cnt:
                if cnt[it2] > ct[it2]:
                    flag = False
                    break
            if flag:
                res.append(wd)
                
        return res

c ++ 
class Solution {
public:
    vector<string> wordSubsets(vector<string>& words1, vector<string>& words2) {
        vector<vector<int>> f(words1.size(), vector<int>(26));

        for(int i = 0; i < words1.size(); i ++ ) {
            for(auto c : words1[i]) {
                f[i][c - 'a'] ++ ;
            }
        }

        int cnt[26] = {0}, tmp[26] = {0};
        for(int i = 0; i < words2.size(); i ++ ) {
            memset(tmp, 0, sizeof(tmp));
            for(auto c : words2[i]) {
                tmp[c - 'a'] ++ ;
            }
            for(int i = 0; i < 26; i ++ ) {
                cnt[i] = max(cnt[i], tmp[i]);
            }
        }

        vector<string> res;
        for(int i = 0; i < words1.size(); i ++ ) {
            bool flag = true;
            for(int j = 0; j < 26; j ++ ) {
                if(f[i][j] < cnt[j]) {
                    flag = false;
                    break;
                }
            }
            if(flag) res.push_back(words1[i]);
        }

        return res;
    }
};

java
class Solution {

    public int[] count(String s) {
        int[] res = new int[26];
        for(int i = 0; i < s.length(); i ++ ) {
            res[s.charAt(i) - 'a'] ++ ;
        }
        return res;
    }

    public List<String> wordSubsets(String[] words1, String[] words2) {
        int[] cnt = count("");
        for(String it : words2){
            int[] tt = count(it);
            for(int i = 0; i < 26; i ++ ) {
                cnt[i] = Math.max(cnt[i], tt[i]);
            }
        }

        List<String> res = new ArrayList();
        for(String it : words1) {
            int[] tt = count(it);
            boolean flag = true;
            for(int i = 0; i < 26; i ++ ) {
                if(cnt[i] > tt[i]) {
                    flag = false;
                    break;
                }
            }
            if(flag) {
                res.add(it);
            }
        }
        return res;
    }
}

golang
func max(a int, b int) int {
    if a > b {
        return a
    }
    return b
}

func wordSubsets(words1 []string, words2 []string) []string {
    cnt := make([]int, 26)
    for _, val := range words2 {
        tt := make([]int, 26)
        for i := range val {
            tt[val[i] - 'a'] ++ ; 
        }
        for i := range cnt {
            cnt[i] = max(cnt[i], tt[i])
        }
    }

    var res []string
    for _, val := range words1 {
        tt := make([]int, 26)
        for i := range val {
            tt[val[i] - 'a'] ++ 
        }
        flag := true
        for it := range cnt {
            if cnt[it] > tt[it] {
                flag = false
                break
            }
        }
        if flag {
            res = append(res, val)
        }
    }
    
    return res
}

js
/**
 * @param {string[]} words1
 * @param {string[]} words2
 * @return {string[]}
 */
var wordSubsets = function(words1, words2) {
    let cnt = new Array(26).fill(0);
    let res = [];

    for(let i = 0; i < words2.length; i ++ ) {
        let tmp = new Array(26).fill(0);
        for(let j = 0; j < words2[i].length; j ++ ) {
            tmp[words2[i][j].charCodeAt() - 'a'.charCodeAt()] ++ ;
        }
        for(let j = 0; j < 26; j ++ ) {
            cnt[j] = Math.max(cnt[j], tmp[j]);
        }
    }

    for(let i = 0; i < words1.length; i ++ ) {
        let tmp = new Array(26).fill(0);
        for(let j = 0; j < words1[i].length; j ++ ) {
            tmp[words1[i][j].charCodeAt() - 'a'.charCodeAt()] ++ ;
        }
        let flag = true;
        for(let j = 0; j < 26; j ++ ) {
            if(cnt[j] > tmp[j]) {
                flag = false;
                break;
            }
        }
        if(flag) {
            res.push(words1[i]);
        }
    }
    return res;
};