676. 实现一个魔法字典

题目描述

设计一个使用单词列表进行初始化的数据结构，单词列表中的单词 互不相同 。如果给出一个单词，请判定能否只将这个单词中一个字母换成另一个字母，使得所形成的新单词存在于你构建的字典中。

实现 MagicDictionary 类：

MagicDictionary() 初始化对象
void buildDict(String[] dictionary) 使用字符串数组 dictionary 设定该数据结构，dictionary 中的字符串互不相同
bool search(String searchWord) 给定一个字符串 searchWord ，判定能否只将字符串中一个字母换成另一个字母，使得所形成的新字符串能够与字典中的任一字符串匹配。如果可以，返回 true ；否则，返回 false 。

示例：

输入
["MagicDictionary", "buildDict", "search", "search", "search", "search"]
[[], [["hello", "leetcode"]], ["hello"], ["hhllo"], ["hell"], ["leetcoded"]]
输出
[null, null, false, true, false, false]

解释
MagicDictionary magicDictionary = new MagicDictionary();
magicDictionary.buildDict(["hello", "leetcode"]);
magicDictionary.search("hello"); // 返回 False
magicDictionary.search("hhllo"); // 将第二个 'h' 替换为 'e' 可以匹配 "hello" ，所以返回 True
magicDictionary.search("hell"); // 返回 False
magicDictionary.search("leetcoded"); // 返回 False

提示：

1 <= dictionary.length <= 100
1 <= dictionary[i].length <= 100
dictionary[i] 仅由小写英文字母组成
dictionary 中的所有字符串 互不相同
1 <= searchWord.length <= 100
searchWord 仅由小写英文字母组成
buildDict 仅在 search 之前调用一次
最多调用 100 次 search

解法

方法一：直接遍历

对于 $buildDict$ 方法，直接将 $dictionary$ 赋给 $MagicDictionary$ 的成员变量 $d$。

对于 $search$ 方法，遍历单词列表中的每个单词 $w$，依次与 $searchWord$ 进行比对，如果存在一个 $w$，满足 $w$ 与 $searchWord$ 恰好只有一个位置对应的字符不同，那么返回 $true$。

方法二：哈希表 + 模式串

用哈希表 $s$ 存放 $dictionary$ 所有单词，同时生成每个单词的所有模式串，用哈希表 $cnt$ 存放。

模式串的生成规则是：对于一个单词 $w$，我们将每个 $w[i]$ 都替换成 $.$，最终得到一个模式串列表。例如，我们可以生成 $leet$ 的模式串列表为：$[.eet, l.et, le.t, lee.]$。

执行 $search$ 时，我们拿到 $searchWord$ 的模式串列表，然后判断列表中每个模式串 $p$ 是否在 $cnt$ 和 $s$ 中出现过。若 $cnt>1$ 或 $cnt=1$ 且 $searchWord$ 没在 $s$ 中出现过，说明找到了满足条件的单词，返回 $true$。

Python3

class MagicDictionary:
    def __init__(self):
        self.d = None

    def buildDict(self, dictionary: List[str]) -> None:
        self.d = dictionary

    def search(self, searchWord: str) -> bool:
        for w in self.d:
            if len(w) != len(searchWord):
                continue
            diff = sum(a != b for a, b in zip(w, searchWord))
            if diff == 1:
                return True
        return False


# Your MagicDictionary object will be instantiated and called as such:
# obj = MagicDictionary()
# obj.buildDict(dictionary)
# param_2 = obj.search(searchWord)

class MagicDictionary:
    def __init__(self):
        """
        Initialize your data structure here.
        """

    def gen(self, word):
        return [word[:i] + '*' + word[i + 1 :] for i in range(len(word))]

    def buildDict(self, dictionary: List[str]) -> None:
        self.s = set(dictionary)
        self.cnt = Counter(p for word in dictionary for p in self.gen(word))

    def search(self, searchWord: str) -> bool:
        for p in self.gen(searchWord):
            if self.cnt[p] > 1 or (self.cnt[p] == 1 and searchWord not in self.s):
                return True
        return False


# Your MagicDictionary object will be instantiated and called as such:
# obj = MagicDictionary()
# obj.buildDict(dictionary)
# param_2 = obj.search(searchWord)

Java

class MagicDictionary {
    private String[] d;

    public MagicDictionary() {
    }

    public void buildDict(String[] dictionary) {
        d = dictionary;
    }

    public boolean search(String searchWord) {
        for (String w : d) {
            if (w.length() != searchWord.length()) {
                continue;
            }
            int diff = 0;
            for (int i = 0; i < w.length(); ++i) {
                if (w.charAt(i) != searchWord.charAt(i)) {
                    ++diff;
                }
            }
            if (diff == 1) {
                return true;
            }
        }
        return false;
    }
}

/**
 * Your MagicDictionary object will be instantiated and called as such:
 * MagicDictionary obj = new MagicDictionary();
 * obj.buildDict(dictionary);
 * boolean param_2 = obj.search(searchWord);
 */

class MagicDictionary {
    private Set<String> s = new HashSet<>();
    private Map<String, Integer> cnt = new HashMap<>();

    /** Initialize your data structure here. */
    public MagicDictionary() {
    }

    public void buildDict(String[] dictionary) {
        for (String word : dictionary) {
            s.add(word);
            for (String p : gen(word)) {
                cnt.put(p, cnt.getOrDefault(p, 0) + 1);
            }
        }
    }

    public boolean search(String searchWord) {
        for (String p : gen(searchWord)) {
            int v = cnt.getOrDefault(p, 0);
            if (v > 1 || (v == 1 && !s.contains(searchWord))) {
                return true;
            }
        }
        return false;
    }

    private List<String> gen(String word) {
        List<String> res = new ArrayList<>();
        char[] chars = word.toCharArray();
        for (int i = 0; i < chars.length; ++i) {
            char c = chars[i];
            chars[i] = '*';
            res.add(new String(chars));
            chars[i] = c;
        }
        return res;
    }
}

/**
 * Your MagicDictionary object will be instantiated and called as such:
 * MagicDictionary obj = new MagicDictionary();
 * obj.buildDict(dictionary);
 * boolean param_2 = obj.search(searchWord);
 */

C++

class MagicDictionary {
public:
    vector<string> d;

    MagicDictionary() {
    }

    void buildDict(vector<string> dictionary) {
        d = move(dictionary);
    }

    bool search(string searchWord) {
        for (auto&& w : d) {
            if (w.size() != searchWord.size()) continue;
            int diff = 0;
            for (int i = 0; i < w.size(); ++i) diff += w[i] != searchWord[i];
            if (diff == 1) return true;
        }
        return false;
    }
};

/**
 * Your MagicDictionary object will be instantiated and called as such:
 * MagicDictionary* obj = new MagicDictionary();
 * obj->buildDict(dictionary);
 * bool param_2 = obj->search(searchWord);
 */

class MagicDictionary {
public:
    /** Initialize your data structure here. */
    MagicDictionary() {
    }

    void buildDict(vector<string> dictionary) {
        for (string word : dictionary) {
            s.insert(word);
            for (string p : gen(word)) ++cnt[p];
        }
    }

    bool search(string searchWord) {
        for (string p : gen(searchWord)) {
            if (cnt[p] > 1 || (cnt[p] == 1 && !s.count(searchWord))) return true;
        }
        return false;
    }

private:
    unordered_set<string> s;
    unordered_map<string, int> cnt;

    vector<string> gen(string word) {
        vector<string> res;
        for (int i = 0; i < word.size(); ++i) {
            char c = word[i];
            word[i] = '*';
            res.push_back(word);
            word[i] = c;
        }
        return res;
    }
};

/**
 * Your MagicDictionary object will be instantiated and called as such:
 * MagicDictionary* obj = new MagicDictionary();
 * obj->buildDict(dictionary);
 * bool param_2 = obj->search(searchWord);
 */

Go

type MagicDictionary struct {
	d []string
}

func Constructor() MagicDictionary {
	return MagicDictionary{[]string{}}
}

func (this *MagicDictionary) BuildDict(dictionary []string) {
	this.d = dictionary
}

func (this *MagicDictionary) Search(searchWord string) bool {
	for _, w := range this.d {
		if len(w) != len(searchWord) {
			continue
		}
		diff := 0
		for i := range w {
			if w[i] != searchWord[i] {
				diff++
			}
		}
		if diff == 1 {
			return true
		}
	}
	return false
}

/**
 * Your MagicDictionary object will be instantiated and called as such:
 * obj := Constructor();
 * obj.BuildDict(dictionary);
 * param_2 := obj.Search(searchWord);
 */

type MagicDictionary struct {
	s   map[string]bool
	cnt map[string]int
}

/** Initialize your data structure here. */
func Constructor() MagicDictionary {
	return MagicDictionary{map[string]bool{}, map[string]int{}}
}

func (this *MagicDictionary) BuildDict(dictionary []string) {
	for _, word := range dictionary {
		this.s[word] = true
		for _, p := range gen(word) {
			this.cnt[p]++
		}
	}
}

func (this *MagicDictionary) Search(searchWord string) bool {
	for _, p := range gen(searchWord) {
		if this.cnt[p] > 1 || (this.cnt[p] == 1 && !this.s[searchWord]) {
			return true
		}
	}
	return false
}

func gen(word string) []string {
	var res []string
	for i := 0; i < len(word); i++ {
		res = append(res, word[:i]+"."+word[i+1:])
	}
	return res
}

/**
 * Your MagicDictionary object will be instantiated and called as such:
 * obj := Constructor();
 * obj.BuildDict(dictionary);
 * param_2 := obj.Search(searchWord);
 */

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676. 实现一个魔法字典

题目描述

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Python3

Java

C++

Go

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676. 实现一个魔法字典

题目描述

解法

Python3

Java

C++

Go

...