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  1. Prepare
  2. Algorithms
  3. NP Complete
  4. Spies, Revised
  5. Discussions

Spies, Revised

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  • panji_swahastika
     + 0 comments

    def is_colinear(r1, c1, r2, c2, r3, c3): return (r2 - r1) * (c3 - c1) == (r3 - r1) * (c2 - c1)

    def is_valid(row, col, placement): for r2 in range(row): c2 = placement[r2] if col == c2 or abs(row - r2) == abs(col - c2): return False for r1 in range(r2): c1 = placement[r1] if is_colinear(r1, c1, r2, c2, row, col): return False return True

    def solve(n, placement=[], used_cols=set()): row = len(placement) if row == n: return placement for col in range(n): if col in used_cols: continue if is_valid(row, col, placement): res = solve(n, placement + [col], used_cols | {col}) if res: return res return None

    if name == "main": max_n = 13 for n in range(max_n, 0, -2): result = solve(n) if result: print(n) print(" ".join(str(c + 1) for c in result)) break

  • vitp15
     + 0 comments

    9

    1 7 4 6 9 2 5 3 8

    why this solution is not accepted?

  • solentador
     + 1 comment

    There might be an error in code control, the following output matrix seems true.

    "3 1 4 2 5"

  • [deleted]     + 0 comments

    Works 

    print(9)
print("5 2 4 9 7 3 1 6 8")

  • sarmed_edward
     + 0 comments

    How old is this?

    In year 2000 as a recent Computer Grad, I resolved the Queens on chess board (from Java Deitel and Deitel): That is:

    How many queens can we add into a chess board so that no queen captures the other?! Output is 8, where they are a chess knight distance from each other