comefrom: <doocs>1027.Longest Arithmetic Subsequence_1.py
code: def longestArithSeqLength( nums: List[int]) -> int:
      n = len(nums)
      dp = [[1] * 1001 for _ in range(n)]
      ans = 0
      for i in range(1, n):
          for j in range(i):
              d = nums[i] - nums[j] + 500
              dp[i][d] = max(dp[i][d], dp[j][d] + 1)
              ans = max(ans, dp[i][d])
      return ans
masked: def sample_funcname ( var_0 : List [ int ] ) -> int :
      var_4 = len ( var_0 )
      var_9 = [ [ 1 ] * 1001 for var_7 in range ( var_4 ) ]
      var_11 = 0
      for var_12 in range ( 1 , var_4 ) :
          for var_13 in range ( var_12 ) :
              var_15 = var_0 [ var_12 ] - var_0 [ var_13 ] + 500
              var_9 [ var_12 ] [ var_15 ] = max ( var_9 [ var_12 ] [ var_15 ] , var_9 [ var_13 ] [ var_15 ] + 1 )
              var_11 = max ( var_11 , var_9 [ var_12 ] [ var_15 ] )
      return var_11
  