mirror of
https://github.com/TheAlgorithms/Ruby
synced 2024-12-27 21:58:57 +01:00
42 lines
835 B
Ruby
42 lines
835 B
Ruby
# Challenge name: 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.
|
|
#
|
|
# @param {Integer[]} nums
|
|
# @return {Integer}
|
|
#
|
|
|
|
#
|
|
# Approach 1: Brute Force
|
|
#
|
|
# Time Complexity: O(n^2)
|
|
#
|
|
def num_identical_pairs(nums)
|
|
count = 0
|
|
nums.each_with_index do |num, i|
|
|
target = num
|
|
nums.each_with_index do |num, j|
|
|
next if i >= j
|
|
if num == target
|
|
count += 1
|
|
end
|
|
end
|
|
end
|
|
count
|
|
end
|
|
|
|
nums = [1, 2, 3, 1, 1, 3]
|
|
puts(num_identical_pairs(nums))
|
|
# Output: 4
|
|
# Explanation: There are 4 good pairs (0,3), (0,4), (3,4), (2,5) 0-indexed.
|
|
|
|
nums = [1, 1, 1, 1]
|
|
puts(num_identical_pairs(nums))
|
|
# Output: 6
|
|
# Explanation: Each pair in the array are good.
|
|
|
|
nums = [1, 2, 3]
|
|
puts(num_identical_pairs(nums))
|
|
# Output: 0
|