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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 <= 2001 <= nums[i] <= 100
Solution
# @param {Integer[]} nums
# @return {Boolean}
def can_partition(nums)
sums = nums.sum
return false if sums.odd?
sums /= 2
dp = Array.new(sums + 1, false)
dp[0] = true
nums.each do |num|
sums.downto(num) do |sum|
dp[sum] = dp[sum] || dp[sum - num]
end
end
dp[sums]
end