carloscn
commented
1 year ago Analysis
pub fn count_quadruplets(nums: Vec<i32>) -> i32
{
if nums.len() < 4 {
return -1;
}
let mut ret:i32 = 0;
let len:usize = 1 << nums.len();
for mask in 0..len {
// count '1' bits number
{
let mut count:usize = 0;
let mut t_mask:usize = mask;
while t_mask != 0 {
t_mask &= t_mask - 1;
count += 1;
}
if count != 4 {
continue;
}
}
// judge the numbers
{
let mut cv:Vec<i32> = vec![];
for i in 0..nums.len() {
if mask & (1 << i) != 0 {
cv.push(nums[i]);
}
}
if cv[0] + cv[1] + cv[2] == cv[3] {
ret += 1;
}
}
}
return ret;
}
Description
Given a 0-indexed integer array nums, return the number of distinct quadruplets (a, b, c, d) such that:
nums[a] + nums[b] + nums[c] == nums[d], and a < b < c < d
Example 1:
Input: nums = [1,2,3,6] Output: 1 Explanation: The only quadruplet that satisfies the requirement is (0, 1, 2, 3) because 1 + 2 + 3 == 6.
Example 2:
Input: nums = [3,3,6,4,5] Output: 0 Explanation: There are no such quadruplets in [3,3,6,4,5].
Example 3:
Input: nums = [1,1,1,3,5] Output: 4 Explanation: The 4 quadruplets that satisfy the requirement are:
Constraints: