1726-TupleWithSameProduct.go

package main

// 1726. Tuple with Same Product
// Given an array nums of distinct positive integers, 
// return the number of tuples (a, b, c, d) such that a * b = c * d where a, b, c, and d are elements of nums, and a != b != c != d.

// Example 1:
// Input: nums = [2,3,4,6]
// Output: 8
// Explanation: There are 8 valid tuples:
// (2,6,3,4) , (2,6,4,3) , (6,2,3,4) , (6,2,4,3)
// (3,4,2,6) , (4,3,2,6) , (3,4,6,2) , (4,3,6,2)

// Example 2:
// Input: nums = [1,2,4,5,10]
// Output: 16
// Explanation: There are 16 valid tuples:
// (1,10,2,5) , (1,10,5,2) , (10,1,2,5) , (10,1,5,2)
// (2,5,1,10) , (2,5,10,1) , (5,2,1,10) , (5,2,10,1)
// (2,10,4,5) , (2,10,5,4) , (10,2,4,5) , (10,2,5,4)
// (4,5,2,10) , (4,5,10,2) , (5,4,2,10) , (5,4,10,2)

// Constraints:
//     1 <= nums.length <= 1000
//     1 <= nums[i] <= 10^4
//     All elements in nums are distinct.

import "fmt"

func tupleSameProduct(nums []int) int {
    res, n, mp := 0, len(nums), make(map[int]int)
    for i := 0; i < n - 1; i++ {
        for j := i + 1; j < n; j++ {
            mp[nums[i] * nums[j]]++
        }
    }
    for _, v := range mp {
        res += ((v - 1) * v * 4)
    }
    return res
}

func main() {
    // Example 1:
    // Input: nums = [2,3,4,6]
    // Output: 8
    // Explanation: There are 8 valid tuples:
    // (2,6,3,4) , (2,6,4,3) , (6,2,3,4) , (6,2,4,3)
    // (3,4,2,6) , (4,3,2,6) , (3,4,6,2) , (4,3,6,2)
    fmt.Println(tupleSameProduct([]int{2,3,4,6})) // 8
    // Example 2:
    // Input: nums = [1,2,4,5,10]
    // Output: 16
    // Explanation: There are 16 valid tuples:
    // (1,10,2,5) , (1,10,5,2) , (10,1,2,5) , (10,1,5,2)
    // (2,5,1,10) , (2,5,10,1) , (5,2,1,10) , (5,2,10,1)
    // (2,10,4,5) , (2,10,5,4) , (10,2,4,5) , (10,2,5,4)
    // (4,5,2,10) , (4,5,10,2) , (5,4,2,10) , (5,4,10,2)
    fmt.Println(tupleSameProduct([]int{1,2,4,5,10})) // 16
}