add bfs heuristic for N-puzzle

Python/bfs-for-npuzzle.py

@@ -0,0 +1,67 @@
+def get_children(puzzle):
+    output = []
+    m = eval(puzzle)    
+    i = 0
+    while 0 not in m[i]:
+        i += 1          
+
+    j=m[i].index(0)
+
+    if i > 0 :      #MOVE UP
+        m[i][j],m[i-1][j] = m[i-1][j],m[i][j]
+        output.append(str(m))
+        m[i][j],m[i-1][j] = m[i-1][j],m[i][j]
+
+    if i < 3 :     #MOVE DOWN
+        m[i][j],m[i+1][j] = m[i+1][j],m[i][j]
+        output.append(str(m))
+        m[i][j],m[i+1][j] = m[i+1][j],m[i][j]
+
+    if j > 0 :     #MOVE LEFT
+        m[i][j],m[i][j-1] = m[i][j-1],m[i][j]
+        output.append(str(m))
+        m[i][j],m[i][j-1] = m[i][j-1],m[i][j]
+
+    if j < 3 :     #MOVE RIGHT
+        m[i][j],m[i][j+1] = m[i][j+1],m[i][j]
+        output.append(str(m))
+        m[i][j],m[i][j+1] = m[i][j+1],m[i][j]
+
+    return output
+
+
+
+def bfs(puzzle,result):
+    path = {}
+    path[str(puzzle)] = None
+    queue = []
+    queue.append(str(puzzle))
+    visited = {}
+    visited[str(puzzle)] = 1
+    nodes = 0
+    while queue:
+        # import pdb; pdb.set_trace()
+        path_ = queue.pop(0)
+        # import pdb; pdb.set_trace()
+        if path_ == str(result):
+            print("Solved")
+            print(path_)
+            break
+
+        childnode = get_children(str(path_))
+        for child in childnode:
+            if child not in visited:
+                queue.append(child)
+                visited[child] = 1
+                path[child]= path_
+        nodes = nodes + 1
+        print(nodes)
+
+def main():
+    puzzle = [[1, 2, 6, 3],[4, 9, 5, 7], [8, 13, 11, 15],[12, 14, 0, 10]]
+    result = [[0, 1, 2, 3],[4, 5, 6, 7], [8, 9, 10, 11],[12, 13, 14, 15]]
+
+    bfs(puzzle,result)
+    # dfs(puzzle,result)
+
+main()