backtrack.py

python_prototype/backtrack.py

@@ -7,6 +7,7 @@ from time import sleep
 # PADDING = int(os.popen('tput cols').read()) // 3 # '// 2 - 6' for exact middle for n=4
 PADDING = 5
 DEBUG = False
+ITER = -1
 
 def get_board_dim(board: list) -> int:
     return int(len(board) ** 0.5)
@@ -60,36 +61,47 @@ def get_constraints(board: list, border: list, pos: int) -> list:
     constraints = [colup, coldown, rowleft, rowright]
     return constraints
 
-def check_constraint(slice: list, constraint: int, n: int) -> bool:
+def check_constraint(slice: list, constraint: int) -> bool:
+    global ITER
+
     constraint = int(constraint)
-    if 0 in slice:
-        return True
-    level = 0
+    peak = 0
     visible_towers = 0
 
-    # no board_dim     in 0 to i-2 (inclusive)
-    # no board_dim-1   in 0 to i-3
-    # no board_dim-2   in 0 to i-4
-    # no board_dim-3   in 0 to i-5
-    # ...
-    # no board_dim-i+2 in 0 to 0
+    if slice[0] == 0:
+        return True
 
     board_dim = len(slice)
+    # print()
     for i, tower in enumerate(slice):
-        if tower > level:
-            level = tower
+        if tower > peak:
+            peak = tower
             visible_towers += 1
-        if 
-    return visible_towers == constraint
+        # print(f'{i=} {tower=} {peak=} {visible_towers=} {constraint=} {ITER=}')
+        if visible_towers > constraint:
+            return False
+        if constraint + tower > board_dim + 1 + i:
+            return False
+    if 0 not in slice:
+        return visible_towers == constraint
+    else:
+        return True
 
 def is_valid_state(board: list, border: list, next_candidate_index: int) -> bool:
+    global ITER
+
     row = get_row(board, next_candidate_index)
     column = get_col(board, next_candidate_index)
     constraints = get_constraints(board, border, next_candidate_index)
+    ITER += 1
+    if ITER % 100000 == 0:
+        os.system('clear')
+        print_board(board, border)
+        print(f'{ITER=}')
     satisfies_constraints = all([
         check_constraint(column,       constraints[0]),
-        check_constraint(column[::-1], constraints[1]),
         check_constraint(row,          constraints[2]),
+        check_constraint(column[::-1], constraints[1]),
         check_constraint(row[::-1],    constraints[3]),
     ])
     return satisfies_constraints
@@ -156,11 +168,14 @@ def main(*args, **kwargs) -> None:
     # print(solutions)
 
 if __name__ == '__main__':
-    # main('1 1 1 1')
-    # main('2 1 1 2 2 1 1 2')
-    # main('3 2 1 1 2 2 3 2 1 1 2 2')
+    # main('1 1 1 1') # 1 x 1
+    # main('2 1 1 2 2 1 1 2') # 2 x 2
+    # main('3 2 1 1 2 2 3 2 1 1 2 2') # 3 x 3
     # main('4 3 2 1 1 2 2 2 4 3 2 1 1 2 2 2') # original problem
+    # main('') # original problem
     # main('3 2 2 1 1 2 1 1 4 2 1 2 1 2 2 2') # henri's problem
-    # main('2 1 2 3 3 2 3 1 3 2 2 1 3 3 2 3 4 2 1 2')
-    # main('1 2 2 4 3 5 4 4 2 2 2 1 1 2 3 4 2 4 5 3 3 2 2 1')
-    # main('6 3 1 3 3 3 2 1 2 3 3 3 3 3 3 7 3 4 3 2 1 2 1 2 2 3 3 4')
+    # main('2 1 2 3 3 2 3 1 3 2 2 1 3 3 2 3 4 2 1 2') # 5 x 5
+    # main('1 2 2 4 3 5 4 4 2 2 2 1 1 2 3 4 2 4 5 3 3 2 2 1') # 6 x 6
+    # main('6 3 1 3 3 3 2 1 2 3 3 3 3 3 3 7 3 4 3 2 1 2 1 2 2 3 3 4') # 7 x 7
+    # main('7 4 2 3 3 2 1 1 2 2 2 3 4 6 6 5 4 2 3 2 1 1 2 2 4 2 4 4') # 7 x 7
+    main('4 3 4 1 5 4 3 2 2 4 2 4 1 3 5 4 3 3 5 2 3 1 3 2 2 1 2 3 2 4 3 3') # 8 x 8