1512. Number of Good Pairs #

Problem #

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.

Example 3:

Input: nums = [1,2,3]
Output: 0

Constraints:

• 1 <= nums.length <= 1000
• 1 <= nums[i] <= 100

Problem Summary #

Given an integer array nums. If a pair of numbers (i,j) satisfies nums[i] == nums[j] and i < j, it can be considered a good pair. Return the number of good pairs.

Solution Approach #

• An easy problem. According to the definition of good pairs in the problem, loop through and check whether two numbers are equal, accumulating the count.

Code #

package leetcode

func numIdenticalPairs(nums []int) int {
	total := 0
	for x := 0; x < len(nums); x++ {
		for y := x + 1; y < len(nums); y++ {
			if nums[x] == nums[y] {
				total++
			}
		}
	}
	return total
}