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LeetCode 748 最短补全词

给你一个字符串 licensePlate 和一个字符串数组 words ，请你找出并返回 words 中的 最短补全词 。

补全词 是一个包含 licensePlate 中所有的字母的单词。在所有补全词中，最短的那个就是 最短补全词 。

在匹配 licensePlate 中的字母时：

忽略 licensePlate 中的 数字和空格 。
不区分大小写。
如果某个字母在 licensePlate 中出现不止一次，那么该字母在补全词中的出现次数应当一致或者更多。

例如：licensePlate = "aBc 12c"，那么它的补全词应当包含字母 'a'、'b' （忽略大写）和两个 'c' 。可能的 补全词 有 "abccdef"、"caaacab" 以及 "cbca" 。

请你找出并返回 words 中的 最短补全词 。题目数据保证一定存在一个最短补全词。当有多个单词都符合最短补全词的匹配条件时取 words 中 最靠前的 那个。

示例 1：

输入：licensePlate = "1s3 PSt", words = ["step", "steps", "stripe", "stepple"]
输出："steps"
解释：最短补全词应该包括 "s"、"p"、"s"（忽略大小写） 以及 "t"。
"step" 包含 "t"、"p"，但只包含一个 "s"，所以它不符合条件。
"steps" 包含 "t"、"p" 和两个 "s"。
"stripe" 缺一个 "s"。
"stepple" 缺一个 "s"。
因此，"steps" 是唯一一个包含所有字母的单词，也是本例的答案。

示例 2：

输入：licensePlate = "1s3 456", words = ["looks", "pest", "stew", "show"]
输出："pest"
解释：licensePlate 只包含字母 "s" 。所有的单词都包含字母 "s" ，其中 "pest"、"stew"、和 "show" 三者最短。答案是 "pest" ，因为它是三个单词中在 words 里最靠前的那个。

示例 3：

输入：licensePlate = "Ah71752", words = ["suggest","letter","of","husband","easy","education","drug","prevent","writer","old"]
输出："husband"

示例 4：

输入：licensePlate = "OgEu755", words = ["enough","these","play","wide","wonder","box","arrive","money","tax","thus"]
输出："enough"

示例 5：

输入：licensePlate = "iMSlpe4", words = ["claim","consumer","student","camera","public","never","wonder","simple","thought","use"]
输出："simple"

提示：

1 <= licensePlate.length <= 7
licensePlate 由数字、大小写字母或空格 ' ' 组成
1 <= words.length <= 1000
1 <= words[i].length <= 15
words[i] 由小写英文字母组成

哈希

/**
 * 哈希
 * @param licensePlate
 * @param words
 * @return
 */
public static String shortestCompletingWord(String licensePlate, String[] words) {
    if (licensePlate == null || words == null || words.length == 0) return "";

    int[] chNums = new int[26];
    for (char c : licensePlate.toCharArray()) {
        if (c >= 'A' && c <= 'Z') c += ('a' - 'A');
        if (c >= 'a' && c <= 'z') {
            chNums[c - 'a']++;
        }
    }

    int idx = -1, len = Integer.MAX_VALUE;
    for (int i = 0; i < words.length; i++) {
        boolean flag = true;
        int[] chTmpNums = new int[26];
        for (char c : words[i].toCharArray()) {
            if (c >= 'A' && c <= 'Z') c += ('a' - 'A');

            if ((c >= 'a' && c <= 'z')) {
                chTmpNums[c - 'a']++;
            }
        }
        for (int j = 0; j < 26; j++) {
            if (chTmpNums[j] < chNums[j]) {
                flag = false;
                break;
            }
        }

        if (flag && len > words[i].length()) {
            idx = i;
            len = words[i].length();
        }
    }
    return idx == -1 ? "" : words[idx];
}

测试用例

public static void main(String[] args) {
    String licensePlate = "1s3 PSt";
    String[] words = new String[]{"step", "steps", "stripe", "stepple"};
    String ansStr = ShortestCompletingWord.shortestCompletingWord(licensePlate, words);
    System.out.println("ShortestCompletingWord demo01 result : " + ansStr);

    licensePlate = "1s3 456";
    words = new String[]{"looks", "pest", "stew", "show"};
    ansStr = ShortestCompletingWord.shortestCompletingWord(licensePlate, words);
    System.out.println("ShortestCompletingWord demo02 result : " + ansStr);

    licensePlate = "Ah71752";
    words = new String[]{"suggest", "letter", "of", "husband", "easy", "education", "drug", "prevent", "writer", "old"};
    ansStr = ShortestCompletingWord.shortestCompletingWord(licensePlate, words);
    System.out.println("ShortestCompletingWord demo03 result : " + ansStr);

    licensePlate = "OgEu755";
    words = new String[]{"enough", "these", "play", "wide", "wonder", "box", "arrive", "money", "tax", "thus"};
    ansStr = ShortestCompletingWord.shortestCompletingWord(licensePlate, words);
    System.out.println("ShortestCompletingWord demo04 result : " + ansStr);

    licensePlate = "iMSlpe4";
    words = new String[]{"claim", "consumer", "student", "camera", "public", "never", "wonder", "simple", "thought", "use"};
    ansStr = ShortestCompletingWord.shortestCompletingWord(licensePlate, words);
    System.out.println("ShortestCompletingWord demo05 result : " + ansStr);
}

测试结果

ShortestCompletingWord demo01 result : steps
ShortestCompletingWord demo02 result : pest
ShortestCompletingWord demo03 result : husband
ShortestCompletingWord demo04 result : enough
ShortestCompletingWord demo05 result : simple