LeetCode - Number of Good Pairs Solution - The Coding Shala

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In this post, we will learn how to solve LeetCode's Number of Good Pairs problem and will implement its solution in Java.

Number of Good Pairs

Given an array of integers nums. A pair (i,j) is called good if nums[i] == nums[j] and i < j. Return the number of good pairs.

Example 1:
Input: nums = [1,2,3,1,1,3]
Output: 4
Explanation: There are 4 good pairs (0,3), (0,4), (3,4), (2,5) 0-indexed.

Example 2:
Input: nums = [1,1,1,1]
Output: 6
Explanation: Each pair in the array are good.

Practice this problem on LeetCode: (Click Here).

Number of Good Pairs Java Solution

Approach 1:
Using two loops.
Time Complexity: O(n^2).

Java Program: 

class Solution {
    public int numIdenticalPairs(int[] nums) {
        int ans = 0;
        for(int i=0; i<nums.length-1; i++) {
            for(int j=i+1; j<nums.length; j++) {
                if(nums[i] == nums[j]) ans++;
            }
        }
        return ans;
    }
}


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