0771. Jewels and Stones

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


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

题目大意 #

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。

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。

解题思路 #

  • 给出 2 个字符串,要求在 S 字符串中找出在 J 字符串里面出现的字符个数。这是一道简单题。

代码 #

package leetcode

import "strings"

// 解法一
func numJewelsInStones(J string, S string) int {
	count := 0
	for i := range S {
		if strings.Contains(J, string(S[i])) {
	return count

// 解法二
func numJewelsInStones1(J string, S string) int {
	cache, result := make(map[rune]bool), 0
	for _, r := range J {
		cache[r] = true
	for _, r := range S {
		if _, ok := cache[r]; ok {
	return result



Calendar Apr 17, 2021
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