760. Find Anagram Mappings

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].

760. Find Anagram Mappings
struct Solution;

use std::collections::HashMap;

impl Solution {
fn anagram_mappings(a: Vec<i32>, b: Vec<i32>) -> Vec<i32> {
let mut hs: HashMap<i32, Vec<i32>> = HashMap::new();
let n = a.len();
for (i, &x) in b.iter().enumerate() {
let indexes = hs.entry(x).or_default();
indexes.push(i as i32);
}
let mut res: Vec<i32> = vec![0; n];
for (i, &x) in a.iter().enumerate() {
let indexes = hs.entry(x).or_default();
res[i] = indexes.pop().unwrap();
}
res
}
}

#[test]
fn test() {
let a = vec![12, 28, 46, 32, 50];
let b = vec![50, 12, 32, 46, 28];
let res = vec![1, 4, 3, 2, 0];
assert_eq!(Solution::anagram_mappings(a, b), res);
}