LeetCode：用HashMap解决问题

LeetCode：用HashMap解决问题

Find Anagram Mappings

class Solution {
    public int[] anagramMappings(int[] A, int[] B) {
        Map<Integer, Integer> D = new HashMap();
        for (int i = 0; i < B.length; ++i)
            D.put(B[i], i);

        int[] ans = new int[A.length];
        int t = 0;
        for (int x: A)
            ans[t++] = D.get(x);
        return ans;
    }
}

思考：用字典来解决问题，巧妙将数组编号转换为页码，然后快速查表！

 771.Jewels and Stones

class Solution {
    public int numJewelsInStones(String J, String S) {
        int result = 0;
        HashMap<Character,Integer> jMap = new HashMap<>();
        for(int i=0;i<J.length();i++)
            jMap.put(J.charAt(i),i);
        for(int i=0;i<S.length();i++)
        {
            if(jMap.containsKey(S.charAt(i)))
                result++;
        }
        return result;
    }
}