Count Items Matching a Rule LeetCode Solution - The Coding Shala

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 In this post, we will learn how to solve LeetCode's Count Items Matching a Rule Problem and will implement its solution in Java.

Count Items Matching a Rule Problem

You are given an array items, where each items[i] = [typei, colori, namei] describes the type, color, and name of the ith item. You are also given a rule represented by two strings, ruleKey and ruleValue. The ith item is said to match the rule if one of the following is true:
  • ruleKey == "type" and ruleValue == typei.
  • ruleKey == "color" and ruleValue == colori.
  • ruleKey == "name" and ruleValue == namei.
Return the number of items that match the given rule.

Example 1:
Input: items = [["phone","blue","pixel"],["computer","silver","lenovo"],["phone","gold","iphone"]], ruleKey = "color", ruleValue = "silver"
Output: 1
Explanation: There is only one item matching the given rule, which is ["computer","silver","lenovo"].

Example 2:
Input: items = [["phone","blue","pixel"],["computer","silver","phone"],["phone","gold","iphone"]], ruleKey = "type", ruleValue = "phone"
Output: 2
Explanation: There are only two items matching the given rule, which are ["phone","blue","pixel"] and ["phone","gold","iphone"]. Note that the item ["computer","silver","phone"] does not match.

Practice this problem on LeetCode.

LeetCode - Count Items Matching a Rule Java Solution

Approach 1

Simple solution using loop and if conditions.

Java Program: 

class Solution {
    public int countMatches(List<List<String>> items, String ruleKey, String ruleValue) {
        int count = 0;
        // loop through the items
        for(List<String> list : items) {
            if(ruleKey.equals("type") && ruleValue.equals(list.get(0))) count++;
            else if(ruleKey.equals("color") && ruleValue.equals(list.get(1))) count++;
            else if(ruleKey.equals("name") && ruleValue.equals(list.get(2))) count++;
        }
        return count;
    }
}


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