Program to find number of good pairs in Python

Suppose we have an array nums. Here a pair (i,j) is said to be a good pair if nums[i] is same as nums[j] and i < j. We have to count the number of good pairs.

So, if the input is like nums = [5,6,7,5,5,7], then the output will be 4 as there are 4 good pairs the indices are (0, 3), (0, 4) (3, 4), (2, 5)

To solve this, we will follow these steps −

• count:= 0

• n:= size of nums

• for i in range 0 to n - 1, do

  • for j in range i+1 to n - 1, do

    • if nums[i] is same as nums[j], then

      • count := count + 1

• return count

Example (Python)

Let us see the following implementation to get better understanding −

 Live Demo

def solve(nums):
   count=0
   n=len(nums)
   for i in range(n):
      for j in range(i+1,n):
         if nums[i] == nums[j]:
            count+=1
   return count

nums = [5,6,7,5,5,7]
print(solve(nums))

Input

[5,6,7,5,5,7]

Output

4