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.
Rust Solution
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);
}
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