LeetCode in Kotlin
1755. Closest Subsequence Sum
Hard
You are given an integer array nums and an integer goal.
You want to choose a subsequence of nums such that the sum of its elements is the closest possible to goal. That is, if the sum of the subsequence’s elements is sum, then you want to minimize the absolute difference abs(sum - goal).
Return the minimum possible value of abs(sum - goal).
Note that a subsequence of an array is an array formed by removing some elements (possibly all or none) of the original array.
Example 1:
Input: nums = [5,-7,3,5], goal = 6
Output: 0
Explanation: Choose the whole array as a subsequence, with a sum of 6. This is equal to the goal, so the absolute difference is 0.
Example 2:
Input: nums = [7,-9,15,-2], goal = -5
Output: 1
Explanation: Choose the subsequence [7,-9,-2], with a sum of -4. The absolute difference is abs(-4 - (-5)) = abs(1) = 1, which is the minimum.
Example 3:
Input: nums = [1,2,3], goal = -7
Output: 7
Constraints:
1 <= nums.length <= 40-107 <= nums[i] <= 107-109 <= goal <= 109
Solution
class Solution {
private var idx = 0
private var sum = 0
fun minAbsDifference(nums: IntArray, goal: Int): Int {
val n = nums.size
val nFirst = Math.pow(2.0, n.toDouble() / 2).toInt()
val nSecond = Math.pow(2.0, (n - n / 2).toDouble()).toInt()
val first = IntArray(nFirst)
val second = IntArray(nSecond)
helper(nums, first, 0, n / 2 - 1)
sum = 0
idx = sum
helper(nums, second, n / 2, n - 1)
first.sort()
second.sort()
var low = 0
var high = nSecond - 1
var ans = Int.MAX_VALUE
while (low < nFirst && high >= 0) {
val localSum = first[low] + second[high]
ans = Math.min(ans, Math.abs(localSum - goal))
if (ans == 0) {
break
}
if (localSum < goal) {
low++
} else {
high--
}
}
return ans
}
private fun helper(nums: IntArray, arr: IntArray, start: Int, end: Int) {
for (i in start..end) {
sum += nums[i]
arr[idx++] = sum
helper(nums, arr, i + 1, end)
sum -= nums[i]
}
}
}