Make Number of Distinct Characters Equal — LeetCode 2531 Python Solution

The problem

You are given two 0-indexed strings word1 and word2. A move consists of choosing two indices i and j such that 0 <= i < word1.length and 0 <= j < word2.length and swapping word1[i] with word2[j].

Example

Input

word1 = "ac", word2 = "b"

Output

false

Explanation

Any pair of swaps would yield two distinct characters in the first string, and one in the second string.

Python solution

class Solution:
    def isItPossible(self, word1: str, word2: str) -> bool:
        cnt1 = Counter(word1)
        cnt2 = Counter(word2)
        x, y = len(cnt1), len(cnt2)
        for c1, v1 in cnt1.items():
            for c2, v2 in cnt2.items():
                if c1 == c2:
                    if x == y:
                        return True
                else:
                    a = x - (v1 == 1) + (cnt1[c2] == 0)
                    b = y - (v2 == 1) + (cnt2[c1] == 0)
                    if a == b:
                        return True
        return False

Complexity

Pattern: Hash Map

Trade memory for time: remember what you have seen so the second pass never happens. LeetCode 2531. Make Number of Distinct Characters Equal is filed here on both counts: the reference solution below belongs to the algorithm family this hub collects, and LeetCode tags it Hash Table and Counting.

The hash map guide has the Python template for the pattern and the 709 LeetCode problems that use it.

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