LeetCode #244 - Shortest Word Distance II

最新推荐文章于 2025-06-03 21:35:50 发布

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本文介绍了一种高效算法，用于查找列表中两指定单词的最短距离。通过使用哈希表存储单词下标，实现快速查找，适用于重复调用场景。示例展示了如何在给定单词列表中计算两词间最短距离。

题目描述：

Design a class which receives a list of words in the constructor, and implements a method that takes two words word1 and word2 and return the shortest distance between these two words in the list. Your method will be called repeatedly many times with different parameters.

Example:
Assume that words = ["practice", "makes", "perfect", "coding", "makes"].

Input: word1 = “coding”, word2 = “practice”

Output: 3

Input: word1 = "makes", word2 = "coding"

Output: 1

Note: You may assume that word1 does not equal to word2, and word1 and word2 are both in the list.

用哈希表存储每个单词出现的下标，用两个指针遍历下标数组找到下标之差的最小值。

class WordDistance {
public:
    WordDistance(vector<string> words) {
        for(int i=0;i<words.size();i++)
        {
            if(hash.count(words[i])==0) hash[words[i]]={i};
            else hash[words[i]].push_back(i);
        }
    }
    
    int shortest(string word1, string word2) {
        vector<int> v1=hash[word1];
        vector<int> v2=hash[word2];
        int i=0, j=0;
        int result=INT_MAX;
        while(i<v1.size()&&j<v2.size())
        {
            result=min(result,abs(v1[i]-v2[j]));
            if(v1[i]<=v2[j]) i++;
            else j++;
        }
        return result;
    }
    
private:
    unordered_map<string,vector<int>> hash;
};