# 1773. Count Items Matching a Rule

Easy
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.
Constraints:
• `1 <= items.length <= 104`
• `1 <= typei.length, colori.length, namei.length, ruleValue.length <= 10`
• `ruleKey` is equal to either `"type"`, `"color"`, or `"name"`.
• All strings consist only of lowercase letters.

### 解題

Runtime: 30 ms, faster than 98.75%
Memory Usage: 6.9 MB, less than 72.50%
func countMatches(items [][]string, ruleKey string, ruleValue string) int {
ans := 0
if ruleKey == "type" {
for _, item := range items {
if item[0] == ruleValue { ans++ }
}
} else if ruleKey == "color" {
for _, item := range items {
if item[1] == ruleValue { ans++ }
}
} else {
for _, item := range items {
if item[2] == ruleValue { ans++ }
}
}
return ans
}