leetcode：2085. 统计出现过一次的公共字符串

题目来源

• leetcode

题目描述

题目解析

class Solution {
public:
    int countWords(vector<string>& words1, vector<string>& words2) {
        std::unordered_map<std::string, int> mapper1, mapper2;
        for(auto & word : words1){  // 可能会出现3次、5次，所以不能用set
            mapper1[word]++;
        }
        
        int ans = 0;
        for(auto & word : words2){
            if(mapper1[word] == 1){  // 只有words1中刚好出现过一次的才能加入备选
                if(mapper2.count(word)){  // 如果word在words2出现次数超过1
                    --ans;
                    mapper1.erase(word); // 那么word从mapper1中移除
                }else{
                    ++ans;
                    mapper2[word]++;  // 记录出现次数
                }
            }
        }
        return ans;
    }
};

class Solution {
public:
    int countWords(vector<string>& words1, vector<string>& words2) {
        std::unordered_map<std::string, int> freq1, freq2;  
        for(auto & word : words1){
            ++freq1[word];
        }
        for(auto & word : words2){
            ++freq2[word];
        }
        int ans  = 0;
        for(const auto &[word, freq] : freq1){
            if(freq == 1 && freq2[word] == 1){
                ++ans;
            }
        }
        return ans;
    }
};