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ARC Task 08ed6ac7 - Column Height Ranking

Task Description

This ARC task involves ranking vertical columns of 5s by their height. The input grid contains columns of 5s that extend from different starting rows to the bottom. The output replaces each 5 with a color (1-4) based on the column's height rank:

  • Color 1: Tallest column (most 5s)
  • Color 2: Second tallest
  • Color 3: Third tallest
  • Color 4: Shortest column

Evolution Summary

Generation Bytes Score Key Changes
0 (initial) 529 1971 Verbose working solution with comments
1 223 2277 Remove comments, single-char variables, compress whitespace
2 198 2302 Use zip(*g) to iterate columns, sum for counting
3 195 2305 Use c.get instead of lambda for sort key
4 189 2311 Merge statements with semicolons
5 184 2316 Use (v>0) multiplication trick
6 178 2322 Use m[x] instead of m.get(x,0)
7 157 2343 Use .index() instead of dict lookup
8 156 2344 Use -~ instead of +1
9 150 2350 Remove unnecessary filter (if sum(c))
10 142 2358 Use [*map(sum,zip(*g))] instead of list comprehension

Final Solution (142 bytes)

def solve(g):
 c=[*map(sum,zip(*g))];s=sorted(range(len(c)),key=lambda i:-c[i])
 return[[v and-~s.index(x)for x,v in enumerate(r)]for r in g]

Key Golfing Tricks Used

  1. [*map(sum,zip(*g))] - Transpose grid and sum columns in one expression (saves bytes over list comprehension)

  2. -~x instead of x+1 - Bitwise NOT followed by negation equals increment, saves 1 byte

  3. v and expr - Short-circuit evaluation returns 0 (falsy) when v=0, otherwise evaluates expr

  4. sorted(range(len(c)),key=lambda i:-c[i]) - Sort indices by column sum descending

  5. .index(x)+1 - Get 1-based rank directly from sorted list position

  6. Single-character variables - g, c, s, r, v, x for maximum compression

  7. Semicolons - Chain statements on one line to minimize newline overhead

Algorithm

  1. Transpose the grid using zip(*g) to get columns
  2. Sum each column (counting 5s, since 0s contribute nothing)
  3. Sort column indices by their sums in descending order
  4. For each cell: if value is non-zero, look up its column's rank (index+1)