771. Jewels and Stones

Easy

You're given strings jewels representing the types of stones that are jewels, and stones representing the stones you have. Each character in stones is a type of stone you have. You want to know how many of the stones you have are also jewels.

Letters are case sensitive, so "a" is considered a different type of stone from "A".

Example 1:

Input: jewels = "aA", stones = "aAAbbbb"
Output:
 3

Example 2:

Input: jewels = "z", stones = "ZZ"
Output:
 0

Constraints:

• 1 <= jewels.length, stones.length <= 50

• jewels and stones consist of only English letters.

• All the characters of jewels are unique.

解題

Runtime: 0 ms, faster than 100.00%

Memory Usage: 2.1 MB, less than 55.71%

func numJewelsInStones(jewels string, stones string) int {
    m := make(map[byte]bool)
    
    for i:=0; i<len(jewels); i++ {
        m[jewels[i]] = true
    }
    
    ans := 0
    
    for i:=0; i<len(stones); i++ {
        if m[stones[i]] { ans++ }
    }
    
    return ans
}