[LeetCode] 771. Jewels and Stones

轉自LeetCode

You're given strings J representing the types of stones that are jewels, and S representing the stones you have.  Each character in S

is a type of stone you have.  You want to know how many of the stones you have are also jewels.

The letters in J are guaranteed distinct, and all characters in J and S are letters. Letters are case sensitive, so "a" is considered a different type of stone from "A".

Example 1:

Input: J = "aA", S = "aAAbbbb"
Output: 3

Example 2:

Input: J = "z", S = "ZZ"
Output: 0

Note:

• S and J will consist of letters and have length at most 50.
• The characters in J are distinct.

<Solution>

想法如下

• 用個 HashSet 把 J 存起來，然後歷遍 S 檢查有幾個字元是在 HashSet 裡面

code 如下

Java

	class Solution {
	public int numJewelsInStones(String J, String S) {
	HashSet<Character> set = new HashSet<>();
	for(char c : J.toCharArray()) {
	set.add(c);
	}
	int ans = 0;
	for(char c : S.toCharArray()) {
	if(set.contains(c)) {
	++ans;
	}
	}
	return ans;
	}
	}

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