18.Jewels and Stones(珠宝和石头)
Level:
Easy
题目描述:
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
andJ
will consist of letters and have length at most 50.- The characters in
J
are distinct.
思路分析:
将珠宝包含的字符放进map中,然后遍历石头,如果遍历到的字符出现在map中,那么石头中的珠宝数目就加一。
代码:
class Solution {
public int numJewelsInStones(String J, String S) {
HashMap<Integer,Character>map=new HashMap<>();
int res=0;
if(J==null||S==null)
return res;
for(int i=0;i<J.length();i++){
map.put(i,J.charAt(i));
}
for(int j=0;j<S.length();j++){
if(map.containsValue(S.charAt(j)))
res++;
}
return res;
}
}