PUZZLE #4241: Watershed D8 Flow Model (diff 1)

watershed learn difficulty: 1/7 simulate author: system unsolved

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

DATA

Elevation	`[70, 26, 64, 64, 43, 13, 20, 12], [11, 43, 41, 43, 26, 36, 46, 74], [26, 31, 80, 16, 26, 61, 35, 53], [79, 38, 24, 62, 83, 10, 12, 85], [24, 50, 25, 36, 68, 28, 84, 74], [84, 41, 55, 15, 25, 78, 85, 33], [16, 33, 56, 72, 78, 65, 45, 78], [53, 52, 58, 89, 89, 90, 64, 41]`
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": [
    [
      70,
      26,
      64,
      64,
      43,
      13,
      20,
      12
    ],
    [
      11,
      43,
      41,
      43,
      26,
      36,
      46,
      74
    ],
    [
      26,
      31,
      80,
      16,
      26,
      61,
      35,
      53
    ],
    [
      79,
      38,
      24,
      62,
      83,
      10,
      12,
      85
    ],
    [
      24,
      50,
      25,
      36,
      68,
      28,
      84,
      74
    ],
    [
      84,
      41,
      55,
      15,
      25,
      78,
      85,
      33
    ],
    [
      16,
      33,
      56,
      72,
      78,
      65,
      45,
      78
    ],
    [
      53,
      52,
      58,
      89,
      89,
      90,
      64,
      41
    ]
  ],
  "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 1