Data commit

Task/Peaceful-chess-queen-armies/Python/peaceful-chess-queen-armies-1.py

@@ -0,0 +1,74 @@
+from itertools import combinations, product, count
+from functools import lru_cache, reduce
+
+
+_bbullet, _wbullet = '\u2022\u25E6'
+_or = set.__or__
+
+def place(m, n):
+    "Place m black and white queens, peacefully, on an n-by-n board"
+    board = set(product(range(n), repeat=2))  # (x, y) tuples
+    placements = {frozenset(c) for c in combinations(board, m)}
+    for blacks in placements:
+        black_attacks = reduce(_or,
+                               (queen_attacks_from(pos, n) for pos in blacks),
+                               set())
+        for whites in {frozenset(c)     # Never on blsck attacking squares
+                       for c in combinations(board - black_attacks, m)}:
+            if not black_attacks & whites:
+                return blacks, whites
+    return set(), set()
+
+@lru_cache(maxsize=None)
+def queen_attacks_from(pos, n):
+    x0, y0 = pos
+    a = set([pos])    # Its position
+    a.update((x, y0) for x in range(n))    # Its row
+    a.update((x0, y) for y in range(n))    # Its column
+    # Diagonals
+    for x1 in range(n):
+        # l-to-r diag
+        y1 = y0 -x0 +x1
+        if 0 <= y1 < n:
+            a.add((x1, y1))
+        # r-to-l diag
+        y1 = y0 +x0 -x1
+        if 0 <= y1 < n:
+            a.add((x1, y1))
+    return a
+
+def pboard(black_white, n):
+    "Print board"
+    if black_white is None:
+        blk, wht = set(), set()
+    else:
+        blk, wht = black_white
+    print(f"## {len(blk)} black and {len(wht)} white queens "
+          f"on a {n}-by-{n} board:", end='')
+    for x, y in product(range(n), repeat=2):
+        if y == 0:
+            print()
+        xy = (x, y)
+        ch = ('?' if xy in blk and xy in wht
+              else 'B' if xy in blk
+              else 'W' if xy in wht
+              else _bbullet if (x + y)%2 else _wbullet)
+        print('%s' % ch, end='')
+    print()
+
+if __name__ == '__main__':
+    n=2
+    for n in range(2, 7):
+        print()
+        for m in count(1):
+            ans = place(m, n)
+            if ans[0]:
+                pboard(ans, n)
+            else:
+                print (f"# Can't place {m} queens on a {n}-by-{n} board")
+                break
+    #
+    print('\n')
+    m, n = 5, 7
+    ans = place(m, n)
+    pboard(ans, n)

Task/Peaceful-chess-queen-armies/Python/peaceful-chess-queen-armies-2.py

@@ -0,0 +1,49 @@
+from peaceful_queen_armies_simpler import place
+from itertools import product, count
+
+_bqueenh, _wqueenh = '&#x265b;', '<font color="green">&#x2655;</font>'
+
+def hboard(black_white, n):
+    "HTML board generator"
+    if black_white is None:
+        blk, wht = set(), set()
+    else:
+        blk, wht = black_white
+    out = (f"<br><b>## {len(blk)} black and {len(wht)} white queens "
+           f"on a {n}-by-{n} board</b><br>\n")
+    out += '<table style="font-weight:bold">\n  '
+    tbl = ''
+    for x, y in product(range(n), repeat=2):
+        if y == 0:
+            tbl += '  </tr>\n  <tr valign="middle" align="center">\n'
+        xy = (x, y)
+        ch = ('<span style="color:red">?</span>' if xy in blk and xy in wht
+              else _bqueenh if xy in blk
+              else _wqueenh if xy in wht
+              else "")
+        bg = "" if (x + y)%2 else ' bgcolor="silver"'
+        tbl += f'    <td style="width:14pt; height:14pt;"{bg}>{ch}</td>\n'
+    out += tbl[7:]
+    out += '  </tr>\n</table>\n<br>\n'
+    return out
+
+if __name__ == '__main__':
+    n=2
+    html = ''
+    for n in range(2, 7):
+        print()
+        for m in count(1):
+            ans = place(m, n)
+            if ans[0]:
+                html += hboard(ans, n)
+            else:
+                html += (f"<b># Can't place {m} queen armies on a "
+                         f"{n}-by-{n} board</b><br><br>\n\n" )
+                break
+    #
+    html += '<br>\n'
+    m, n = 6, 7
+    ans = place(m, n)
+    html += hboard(ans, n)
+    with open('peaceful_queen_armies.htm', 'w') as f:
+        f.write(html)