每日一题做题记录，参考官方和三叶的题解

题目要求

思路：模拟

• 就、……、就、定位一下$key$，然后遍历每个相应的$key$找合法的值，定位$key$用哈希表定位或者条件运算符。

Java

哈希表

class Solution {
    public int countMatches(List<List<String>> items, String ruleKey, String ruleValue) {
        int rule = new HashMap<String, Integer>() {{
            put("type", 0);
            put("color", 1);
            put("name", 2);
        }}.get(ruleKey);
        int res = 0;
        for (var i : items) {
            if (i.get(rule).equals(ruleValue))
                res++;
        }
        return res;
    }
}

条件运算符

class Solution {
    public int countMatches(List<List<String>> items, String ruleKey, String ruleValue) {
        int rule = ruleKey.charAt(0) == 't' ? 0 : ruleKey.charAt(0) == 'c' ? 1 : 2;
        int res = 0;
        for (var i : items) {
            if (i.get(rule).equals(ruleValue))
                res++;
        }
        return res;
    }
}

• 时间复杂度：$O(n)$
• 空间复杂度：$O(1)$

C++

哈希表

class Solution {
public:
    int countMatches(vector<vector<string>>& items, string ruleKey, string ruleValue) {
        unordered_map<string, int> ruleDic = {{"type", 0}, {"color", 1}, {"name", 2}};
        int rule = ruleDic[ruleKey], res = 0;
        for (auto i : items) {
            if (i[rule] == ruleValue)
                res++;
        }
        return res;
    }
};

条件运算符

class Solution {
public:
    int countMatches(vector<vector<string>>& items, string ruleKey, string ruleValue) {
        int rule = ruleKey[0] == 't' ? 0 : ruleKey[0] == 'c' ? 1 : 2;
        int res = 0;
        for (auto i : items) {
            if (i[rule] == ruleValue)
                res++;
        }
        return res;
    }
};

• 时间复杂度：$O(n)$
• 空间复杂度：$O(1)$

Rust

• 把match套在数组里就可以一行解决【为了好看还是分了个行】
• rust没有三目表达式，写个if-else还不如这个

impl Solution {
    pub fn count_matches(items: Vec<Vec<String>>, rule_key: String, rule_value: String) -> i32 {
        items.iter().fold(0, |res, i|
            (i[match &rule_key as &str {"type" => 0, "color" => 1, "name" => 2, _=> 3}] == rule_value) as i32 + res)
    }
}

• 时间复杂度：$O(n)$
• 空间复杂度：$O(1)$

总结

• 极致简单模拟题~

欢迎指正与讨论！