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11. Maximum subarray

MediumProgramAcademy Pass20 points

Write maxSubarray xs, the largest sum of a nonempty contiguous run of elements of xs. For [-2, 1, -3, 4, -1, 2, 1, -5, 4] the best run is [4, -1, 2, 1], with sum 6.

For the empty list, return 0. When every element is negative, the answer is the largest single element.

Examples

  1. InputmaxSubarray [-2, 1, -3, 4, -1, 2, 1, -5, 4]Output6
  2. InputmaxSubarray [1]Output1
  3. InputmaxSubarray [5, 4, -1, 7, 8]Output23

Submitting also runs 7 hidden tests.

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Solution.lean
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3#guard (maxSubarray [-2, 1, -3, 4, -1, 2, 1, -5, 4]) = (6)
4#guard (maxSubarray [1]) = (1)
5#guard (maxSubarray [5, 4, -1, 7, 8]) = (23)
examples

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