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 valids 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) , (10,2,4,5)
(4,5,2,10) , (4,5,10,2) , (5,4,2,10) , (5,4,10,2)
```

Example 3:

```Input: nums = [2,3,4,6,8,12]
Output: 40
```

Example 4:

```Input: nums = [2,3,5,7]
Output: 0
```

Constraints:

• `1 <= nums.length <= 1000`
• `1 <= nums[i] <= 104`
• All elements in `nums` are distinct.

1726. Tuple with Same Product
``````struct Solution;

use std::collections::HashMap;

impl Solution {
fn tuple_same_product(nums: Vec<i32>) -> i32 {
let mut count: HashMap<i32, usize> = HashMap::new();
let n = nums.len();
let mut res = 0;
for i in 0..n {
for j in i + 1..n {
let product = nums[i] * nums[j];
let x = count.entry(product).or_default();
res += *x;
*x += 1;
}
}
res as i32 * 8
}
}

#[test]
fn test() {
let nums = vec![2, 3, 4, 6];
let res = 8;
assert_eq!(Solution::tuple_same_product(nums), res);
let nums = vec![1, 2, 4, 5, 10];
let res = 16;
assert_eq!(Solution::tuple_same_product(nums), res);
let nums = vec![2, 3, 4, 6, 8, 12];
let res = 40;
assert_eq!(Solution::tuple_same_product(nums), res);
let nums = vec![2, 3, 5, 7];
let res = 0;
assert_eq!(Solution::tuple_same_product(nums), res);
}
``````