LeetCode 3164: Find the Number of Good Pairs II Solution

Master LeetCode problem 3164 (Find the Number of Good Pairs II), a medium challenge, with our optimized solutions in Java, C++, and Python. Explore detailed explanations, test your code in our interactive editor, and prepare for coding interviews.

3164. Find the Number of Good Pairs II

Medium

Array Hash Table

Problem Explanation

Explanation

To solve this problem, we iterate through each pair of elements from nums1 and nums2, check if the condition for a good pair is satisfied, and increment the count accordingly. We can optimize this process by creating a HashMap to store the remainders of elements in nums2. This way, we can quickly determine if a pair is good or not using the remainders instead of performing division operations.

Initialize a HashMap remainderMap to store the count of remainders in nums2.
Iterate over nums2 and calculate the remainders for each element, storing them in remainderMap.
Iterate over each pair of elements from nums1 and nums2, checking if the pair is good based on the remainders in remainderMap.
Increment the count of good pairs accordingly.

Time Complexity

The time complexity of this solution is O(n + m) where n is the length of nums1 and m is the length of nums2.

Space Complexity

The space complexity of this solution is O(m) where m is the length of nums2.

Solution Code

import java.util.HashMap;

class Solution {
    public int countGoodPairs(int[] nums1, int[] nums2, int k) {
        HashMap<Integer, Integer> remainderMap = new HashMap<>();
        for (int num : nums2) {
            int remainder = num % k;
            remainderMap.put(remainder, remainderMap.getOrDefault(remainder, 0) + 1);
        }

        int goodPairs = 0;
        for (int num : nums1) {
            int remainder = num % k;
            goodPairs += remainderMap.getOrDefault(0, 0) + remainderMap.getOrDefault(k - remainder, 0);
        }

        return goodPairs;
    }
}

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Frequently Asked Questions

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What is the time complexity of LeetCode 3164 (Find the Number of Good Pairs II)?

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