[leetcode] 760. Find Anagram Mappings @ python

原题

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:

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

解法

遍历B, 用字典d储存字母和索引. 遍历A, 从字典中取出索引.

代码

class Solution(object):
    def anagramMappings(self, A, B):
        """
        :type A: List[int]
        :type B: List[int]
        :rtype: List[int]
        """
        # build a dict d[val] = [index]
        d = collections.defaultdict(list)
        for i, val in enumerate(B):
            d[val].append(i)
        
        return [d[val].pop() for val in A]