LeetCode 771: Jewels and Stones Solution
Master LeetCode problem 771 (Jewels and Stones), a easy challenge, with our optimized solutions in Java, C++, and Python. Explore detailed explanations, test your code in our interactive editor, and prepare for coding interviews.
771. Jewels and Stones
Problem Explanation
Explanation
To solve this problem, we can iterate through each stone in the stones string and check if it is present in the jewels string. If it is present, we increment a counter to keep track of the number of stones that are jewels. We can use a Set in Java or a unordered_set in C++ to store the types of jewels for efficient lookup. The time complexity of this approach is O(n), where n is the length of the stones string, and the space complexity is O(m), where m is the number of unique jewels.
Solution Code
import java.util.HashSet;
import java.util.Set;
class Solution {
public int numJewelsInStones(String jewels, String stones) {
Set<Character> jewelSet = new HashSet<>();
for (char jewel : jewels.toCharArray()) {
jewelSet.add(jewel);
}
int count = 0;
for (char stone : stones.toCharArray()) {
if (jewelSet.contains(stone)) {
count++;
}
}
return count;
}
}Try It Yourself
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