【LeetCode题解---771】Jewels and Stones.md

【LeetCode题解—771】Jewels and Stones

题目

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.

词汇

• representing代表
• jewels 珠宝
• stones 石头
• guaranteed 保证

翻译

​ 给定字符串J和S，求S中在J中出现的字符总数。

 注意，区分大小写即a和A不一样。

解法

解法一

* 使用Hash方法

* 通过遍历字符串S和J，两两进行比较，判断stone中有多少颗jewel。

* 时间复杂度为O(s * j)。(s为字符串S的长度，j为字符串J的长度)。

* 空间复杂度为O(1)。

解法二

* 暴力解法

* 时间复杂度：O（n^2）

* 空间复杂度：O（1)

以上代码会同步更新在本人的Github和优快云上

Github地址：https://github.com/Bylant/LeetCode

优快云地址：https://blog.youkuaiyun.com/ZBylant
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