cs471/hw1/dfs.py

#!/usr/bin/env python3

import problem


def depth_limited_search(node, depth):
    if depth == 0:
        if problem.is_goal(node):
            return (node, True)
        return (None, True)
    elif depth > 0:
        print("Depth is now " + str(depth))
        if node == problem.start:
            print("Initial state")
            print(node.to_string())
        any_remaining = False
        for act in node.actions:
            child = act.result_state
            print(act.to_string())
            print(child.to_string())
            found, remaining = depth_limited_search(child, depth - 1)
            if found is not None:
                print("Goal state found")
                return (found, True)
            if remaining:
                any_remaining = True
        return (None, any_remaining)


def iterative_deepening_dfs(root):
    for depth in range(1, 999):
        print("Examining at maximum depth " + str(depth))
        found, remaining = depth_limited_search(root, depth)
        if found is not None:
            return found
        elif not remaining:
            return None
    print("Overflow in iterative deepening depth-first search")


finish = iterative_deepening_dfs(problem.start)
print(finish.to_string())