760. Find Anagram Mappings

2019/10/30 Leetcode

760. Find Anagram Mappings

Tags: ‘Hash Table’

Given two lists Aand B, and B is an anagram of A. B is an anagram of A means B is made by randomizing the order of the elements in A.

We want to find an index mapping P, from A to B. A mapping P[i] = j means the ith element in A appears in B at index j.

These lists A and B may contain duplicates. If there are multiple answers, output any of them.

For example, given

A = [12, 28, 46, 32, 50]
B = [50, 12, 32, 46, 28]

We should return
[1, 4, 3, 2, 0]
as P[0] = 1 because the 0th element of A appears at B[1], and P[1] = 4 because the 1st element of A appears at B[4], and so on.

Note:

  1. A, B have equal lengths in range [1, 100].
  2. A[i], B[i] are integers in range [0, 10^5].

Solution

public int[] anagramMappings(int[] A, int[] B) {
    Map<Integer, Integer> map = new HashMap<>();
    int[] result = new int[A.length];
    for (int i = 0; i < B.length; i++) {
        map.put(B[i], i);
    }
    
    int i = 0;
    for (int a: A) {
        result[i++] = map.get(a);
    }
    return result;
}

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