PUZZLE #4771: Watershed D8 Flow Model (diff 2)

watershed learn difficulty: 2/7 simulate author: system unsolved

A 8×8 elevation grid. Compute D8 flow accumulation — drainage area per cell maps to letters.

DATA

Elevation	`[36, 66, 49, 10, 39, 84, 61, 54], [64, 25, 25, 36, 39, 47, 46, 90], [16, 40, 20, 50, 64, 12, 88, 78], [55, 35, 22, 58, 39, 10, 42, 17], [22, 15, 74, 57, 56, 88, 78, 75], [75, 25, 30, 79, 74, 28, 60, 76], [84, 34, 60, 86, 57, 43, 51, 68], [86, 30, 10, 67, 32, 10, 37, 80]`
Grid Size	`8`
N Chars	`6`
Hint	`For each cell: find lowest neighbor (8-directional). Water flows that way. Accumulate flow from upstream cells. Sort outlet cells by accumulation -> letters.`
Answer Format	`lowercase letters, no spaces or punctuation`

{
  "type": "watershed",
  "elevation": [
    [
      36,
      66,
      49,
      10,
      39,
      84,
      61,
      54
    ],
    [
      64,
      25,
      25,
      36,
      39,
      47,
      46,
      90
    ],
    [
      16,
      40,
      20,
      50,
      64,
      12,
      88,
      78
    ],
    [
      55,
      35,
      22,
      58,
      39,
      10,
      42,
      17
    ],
    [
      22,
      15,
      74,
      57,
      56,
      88,
      78,
      75
    ],
    [
      75,
      25,
      30,
      79,
      74,
      28,
      60,
      76
    ],
    [
      84,
      34,
      60,
      86,
      57,
      43,
      51,
      68
    ],
    [
      86,
      30,
      10,
      67,
      32,
      10,
      37,
      80
    ]
  ],
  "grid_size": 8,
  "n_chars": 6,
  "hint": "For each cell: find lowest neighbor (8-directional). Water flows that way. Accumulate flow from upstream cells. Sort outlet cells by accumulation -> letters.",
  "answer_format": "lowercase letters, no spaces or punctuation"
}

author's note: Pool fill: watershed diff 2