commit 4f44c1442aa56ef0e3b1797733b8cf701bfdd4cb
Author: Andy Teijelo Pérez <ateijelo@gmail.com>
Date:   Sun Nov 20 22:17:41 2016 -0500

    Initial commit

diff --git a/main.py b/main.py
new file mode 100755
index 0000000..0e6a604
--- /dev/null
+++ b/main.py
@@ -0,0 +1,72 @@
+#!/usr/bin/env python3
+
+from itertools import combinations_with_replacement
+
+
+def row_solutions(width, pattern):
+    """
+    This yields a tuple for each possible layout of
+    pattern inside the row. The tuple elements are the
+    amount of cells that must be inserted before each
+    block in pattern. The tuple doesn't include the
+    number of cells at the end of the row since that's
+    just: width - sum(sol) - sum(pattern) 
+    """
+    spaces = width - (sum(pattern) + len(pattern) - 1)
+    for sol in combinations_with_replacement(range(spaces + 1), len(pattern)):
+        sol = sol[0:1] + tuple((sol[i] - sol[i-1] + 1) for i in range(1,len(sol)))
+        yield sol
+
+def expand_solution(solution, width, pattern):
+    """
+    expands a solution to a tuple of 1 (ON) and 0 (OFF) 
+    """
+    r = []
+    for s,p in zip(solution, pattern):
+        r.extend([0] * s)
+        r.extend([1] * p)
+    r.extend([0] * (width - sum(solution) - sum(pattern)))
+    return tuple(r)
+
+
+def matches(expanded_solution, constraints):
+    """
+    solution is a tuple of spaces, the output of row_solutions
+    constraints is a tuple of values from 1, 0 and -1, that
+    mean:
+         0 -> OFF
+         1 -> ON
+        -1 -> not constrained
+    """
+    for s,c in zip(expanded_solution, constraints):
+        if c == -1:
+            continue
+        if c != s:
+            return False
+    return True
+
+
+if __name__ == "__main__":
+    
+    import sys
+
+    def draw(solution, width, pattern):
+        for s,p in zip(solution, pattern):
+            print('.' * s, end="")
+            print('\N{FULL BLOCK}' * p, end="")
+        print('.' * (width - sum(solution) - sum(pattern)))
+
+    width = int(sys.argv[1])
+    pattern = tuple(int(x) for x in sys.argv[2].split())
+    constraints = [-1] * width
+    try:
+        for i,c in enumerate(sys.argv[3]):
+            constraints[i]= {'1':1, '0':0, '?':-1}[c]
+    except:
+        print(sys.exc_info())
+        constraints = [-1] * width
+
+    for solution in row_solutions(width, pattern):
+        e = expand_solution(solution, width, pattern)
+        if matches(e, constraints):
+            draw(solution, width, pattern)
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