LeetCode-in-All

416. Partition Equal Subset Sum

Medium

Given a non-empty array nums containing only positive integers, find if the array can be partitioned into two subsets such that the sum of elements in both subsets is equal.

Example 1:

Input: nums = [1,5,11,5]

Output: true

Explanation: The array can be partitioned as [1, 5, 5] and [11].

Example 2:

Input: nums = [1,2,3,5]

Output: false

Explanation: The array cannot be partitioned into equal sum subsets.

Constraints:

• 1 <= nums.length <= 200
• 1 <= nums[i] <= 100

Solution

object Solution {
    def canPartition(nums: Array[Int]): Boolean = {
        val sum = nums.sum
        if (sum % 2 == 1) {
            false
        } else {
            val targetSum = sum / 2
            val dp = Array.ofDim[Boolean](targetSum + 1)
            dp(0) = true

            for (num <- nums) {
                for (currentSum <- targetSum to num by -1) {
                    dp(currentSum) = dp(currentSum) || dp(currentSum - num)
                }
            }

            dp(targetSum)
        }
    }
}

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