题目:
给定字符串J
代表石头中宝石的类型,和字符串 S
代表你拥有的石头。 S
中每个字符代表了一种你拥有的石头的类型,你想知道你拥有的石头中有多少是宝石。
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.
J
中的字母不重复,J
和 S
中的所有字符都是字母。字母区分大小写,因此"a"
和"A"
是不同类型的石头。
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"
.
示例 1:
输入: J = "aA", S = "aAAbbbb"
输出: 3
示例 2:
输入: J = "z", S = "ZZ"
输出: 0
注意:
-
S
和J
最多含有50个字母。 -
J
中的字符不重复。
Note:
-
S
andJ
will consist of letters and have length at most 50. - The characters in
J
are distinct.
解题思路:
J 改为 Set 集合, 遍历 S 即可(因为 Set 查找复杂度为常数)
Java:
class Solution {
public int numJewelsInStones(String J, String S) {
Set<Character> set = new HashSet<>();
for (char c : J.toCharArray())
set.add(c);
int count = 0;
for (char c : S.toCharArray())
if (set.contains(c)) count++;
return count;
}
}
Python:
class Solution:
def numJewelsInStones(self, J: str, S: str) -> int:
count = 0
hash_set = set(J)
for c in S:
if c in hash_set:
count += 1
return count
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