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  1. def longest_subarray(arr):
  2.     n = len(arr)
  3.  
  4.     if n == 0:
  5.         return None
  6.  
  7.     prefix = [1] * n
  8.     suffix = [1] * n
  9.  
  10.     # Build prefix array (non-increasing)
  11.     for i in range(1, n):
  12.         if arr[i - 1] >= arr[i]:
  13.             prefix[i] = prefix[i - 1] + 1
  14.  
  15.     # Build suffix array (non-decreasing)
  16.     for i in range(n - 2, -1, -1):
  17.         if arr[i] <= arr[i + 1]:
  18.             suffix[i] = suffix[i + 1] + 1
  19.  
  20.     max_len = 0
  21.     start = end = 0
  22.  
  23.     # Find best center
  24.     for i in range(n):
  25.         curr = prefix[i] + suffix[i] - 1
  26.         if curr > max_len:
  27.             max_len = curr
  28.             start = i - prefix[i] + 1
  29.             end = i + suffix[i] - 1
  30.  
  31.     return start, end, max_len, arr[start:end + 1]
  32. arr = [9,8,7,6,5,14,3,2,1,9,8,7,6,5,6,7,8,9,10,11,12,13,24,25,1]
  33. s, e, length, subarray = longest_subarray(arr)
  34.  
  35. print(s, e, length)
  36. print(subarray)
  37.  
Success #stdin #stdout 0.09s 14072KB
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Standard input is empty
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9 23 15
[9, 8, 7, 6, 5, 6, 7, 8, 9, 10, 11, 12, 13, 24, 25]
https://ideone.com/BqqqUi
language:
Python 3 (python  3.12)
created:
13 hours ago
visibility:
public

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