Task · algorithms medium Python ·

Partition into equal sums

def can_partition(nums: list[int]) -> bool:

can_partition([1, 5, 11, 5])  # -> True
can_partition([1, 2, 3, 5])  # -> False

• #1MoonshotAI Kimi K2.7 Codesolved · 11 of 11 testsanswer in 2.5 s · runtime 7 ms · $0.0013

  ✓	can_partition([1, 5, 11, 5])expected True	<1 ms
  ✓	can_partition([1, 2, 3, 5])expected False	<1 ms

  ✓ <1 ms✓ <1 ms✓ <1 ms✓ <1 ms✓ 1 ms✓ <1 ms✓ <1 ms⏱ <1 ms⏱ <1 ms
  Code

  def can_partition(nums: list[int]) -> bool:
      total = sum(nums)
      if total & 1:
          return False
      target = total >> 1
      possible = 1
      for num in nums:
          possible |= possible << num
          if possible >> target & 1:
              return True
      return (possible >> target) & 1 == 1

• #1Anthropic Claude Haiku 5.5solved · 11 of 11 testsanswer in 1.1 s · runtime 16 ms · $0.0001

  ✓	can_partition([1, 5, 11, 5])expected True	<1 ms
  ✓	can_partition([1, 2, 3, 5])expected False	9 ms

  ✓ <1 ms✓ <1 ms✓ <1 ms✓ <1 ms✓ <1 ms✓ <1 ms✓ <1 ms⏱ <1 ms⏱ <1 ms
  Code

  def can_partition(nums: list[int]) -> bool:
      total = sum(nums)
      if total % 2:
          return False
      target = total // 2
      if target == 0:
          return True
      mask = 1
      for x in nums:
          mask |= mask << x
          if (mask >> target) & 1:
              return True
      return bool((mask >> target) & 1)

• #1Qwen3 Coder Nextsolved · 11 of 11 testsanswer in 2.3 s · runtime 19 ms · $0.0002

  ✓	can_partition([1, 5, 11, 5])expected True	1 ms
  ✓	can_partition([1, 2, 3, 5])expected False	<1 ms

  ✓ <1 ms✓ 1 ms✓ <1 ms✓ <1 ms✓ 2 ms✓ <1 ms✓ 6 ms⏱ 1 ms⏱ 3 ms
  Code

  def can_partition(nums: list[int]) -> bool:
      total = sum(nums)
      # If total sum is odd, impossible to split into two equal parts
      if total % 2 != 0:
          return False
      
      target = total // 2
      
      # dp[i] represents whether sum i is achievable
      dp = [False] * (target + 1)
      dp[0] = True  # Sum 0 is always achievable (empty subset)
      
      for num in nums:
          # Traverse from right to left to avoid using the same number twice
          for i in range(target, num - 1, -1):
              if dp[i - num]:
                  dp[i] = True
      
      return dp[target]

• #4SpaceXAI Grok 4.7not solved · 10 of 11 testsanswer in 27 s · runtime 7 ms · $0.01

  ✓	can_partition([1, 5, 11, 5])expected True	1 ms
  ✓	can_partition([1, 2, 3, 5])expected False	<1 ms

  ✗ wrong answer✓ <1 ms✓ <1 ms✓ <1 ms✓ <1 ms✓ <1 ms✓ <1 ms⏱ <1 ms⏱ <1 ms
  Code

  def can_partition(nums: list[int]) -> bool:
      total = sum(nums)
      if total & 1:
          return False
      target = total >> 1
      reachable = 1
      mask = (1 << (target + 1)) - 1
      for x in nums:
          reachable |= (reachable << x) & mask
          if reachable & (1 << target):
              return True
      return False

  Second try

  solved · 11 of 11 testsanswer in 110 s · $0.04

  The model saw how many tests failed, the failing examples with the expected and returned values, and only why hidden tests failed, not their inputs. Doesn't count for places or the rating.

  ✓	can_partition([1, 5, 11, 5])expected True	<1 ms
  ✓	can_partition([1, 2, 3, 5])expected False	<1 ms

  ✓ <1 ms✓ 2 ms✓ <1 ms✓ 1 ms✓ <1 ms✓ <1 ms✓ <1 ms⏱ <1 ms⏱ <1 ms

  Code

  def can_partition(nums: list[int]) -> bool:
      total = sum(nums)
      if total & 1:
          return False
      target = total >> 1
      reachable = 1
      if (reachable >> target) & 1:
          return True
      mask = (1 << (target + 1)) - 1
      for x in nums:
          reachable |= (reachable << x) & mask
          if (reachable >> target) & 1:
              return True
      return False

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