> For the complete documentation index, see [llms.txt](https://mayanktyagi3111.gitbook.io/interview-prep/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://mayanktyagi3111.gitbook.io/interview-prep/hashmap-and-hashset-and-sliding-window/find-anagram-mappings.md).

# Find Anagram Mappings

Given two lists `A` and `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.

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

#### Example

**Example1**

```
Input:  A = [12, 28, 46, 32, 50] and B = [50, 12, 32, 46, 28]
Output: [1, 4, 3, 2, 0]
Explanation:
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.
```

**Example2**

```
Input:  A = [1, 2, 3, 4, 5] and B = [5, 4, 3, 2, 1]
Output: [4, 3, 2, 1, 0]
Explanation:
As P[0] = 4 because the 0th element of A appears at B[4], and P[1] = 3 because the 1st element of A appears at B[3], and so on.
```

```java
public class Solution {
    // O(n) time & O(n) Space
    public int[] anagramMappings(int[] A, int[] B) {
        int[] ans = new int[A.length];
        Map<Integer, List<Integer>> map = new HashMap<>();
        for (int j = 0; j < B.length; j++)
            map.computeIfAbsent(B[j], k -> new ArrayList<>()).add(j);
        for (int i = 0; i < A.length; i++) {
            int size = map.get(A[i]).size();
            ans[i] = map.get(A[i]).get(size - 1);
            map.get(A[i]).remove(size - 1);
        }
        return ans;
    }
}
```