Jewels and Stones Solutions in C++

// Source : https://leetcode.com/problems/jewels-and-stones/description
// Author : Hao Chen
// Date   : 2018-06-23




class Solution {
public:
    int numJewelsInStones(string J, string S) {
        bool map[256] = {false};
        for (auto c : J) {
            map[c]=true;
        }
        int cnt=0;
        for (auto c : S) {
            if (map[c])  cnt++;
        }
        return cnt;
    }
};

/// Source : https://leetcode.com/problems/jewels-and-stones/description/
/// Author : liuyubobobo
/// Time   : 2018-10-06

#include <iostream>
#include <vector>
#include <string>
#include <unordered_set>

using namespace std;


/// Brute Force
/// Time Complexity: O(len(J) * len(S))
/// Space Complxity: O(1)
class Solution {
public:
    int numJewelsInStones(string J, string S) {

        int res = 0;
        for(char c: S)
            if(J.find(c) != string::npos)
                res ++;
        return res;
    }
};


int main() {

    cout << Solution().numJewelsInStones("aA", "aAAbbbb") << endl;
    cout << Solution().numJewelsInStones("z", "ZZ") << endl;

    return 0;
}

/// Source : https://leetcode.com/problems/jewels-and-stones/description/
/// Author : liuyubobobo
/// Time   : 2018-01-27

#include <iostream>
#include <vector>
#include <string>
#include <unordered_set>

using namespace std;


/// Using Hash Set
/// Time Complexity: O(len(J) + len(S))
/// Space Complxity: O(len(J))
class Solution {
public:
    int numJewelsInStones(string J, string S) {

        unordered_set<char> jewels;
        for(char c: J)
            jewels.insert(c);

        int res = 0;
        for(char c: S)
            if(jewels.find(c) != jewels.end())
                res ++;
        return res;
    }
};


int main() {

    cout << Solution().numJewelsInStones("aA", "aAAbbbb") << endl;
    cout << Solution().numJewelsInStones("z", "ZZ") << endl;

    return 0;
}