Q1 dfs

search.py

@@ -18,7 +18,8 @@
 """
 
 import util
-
+from util import Stack
+from util import Queue
 class SearchProblem:
     """
     This class outlines the structure of a search problem, but doesn't implement
@@ -82,17 +83,176 @@ def depthFirstSearch(problem):
     To get started, you might want to try some of these simple commands to
     understand the search problem that is being passed in:
 
+    print("Start:", problem.getStartState())
+    print("Is the start a goal?", problem.isGoalState(problem.getStartState()))
+    print("Start's successors:", problem.getSuccessors(problem.getStartState()))
+    """
+    fringe = Stack()
+    visited = set()
+
+    fringe.push((problem.getStartState(), []))
+
+    while not fringe.isEmpty():
+        node, path = fringe.pop()
+        if problem.isGoalState(node):
+            return path
+
+        if node not in visited:
+            visited.add(node)
+            for successor in problem.getSuccessors(node):
+                fringe.push((successor[0], path + [successor[1]]))
+
+
+
+
+# search.py
+# ---------
+# Licensing Information:  You are free to use or extend these projects for
+# educational purposes provided that (1) you do not distribute or publish
+# solutions, (2) you retain this notice, and (3) you provide clear
+# attribution to UC Berkeley, including a link to http://ai.berkeley.edu.
+#
+# Attribution Information: The Pacman AI projects were developed at UC Berkeley.
+# The core projects and autograders were primarily created by John DeNero
+# (denero@cs.berkeley.edu) and Dan Klein (klein@cs.berkeley.edu).
+# Student side autograding was added by Brad Miller, Nick Hay, and
+# Pieter Abbeel (pabbeel@cs.berkeley.edu).
+
+
+"""
+In search.py, you will implement generic search algorithms which are called by
+Pacman agents (in searchAgents.py).
+
+# Abbreviations
+bfs = breadthFirstSearch
+dfs = depthFirstSearch
+astar = aStarSearch
+ucs = uniformCostSearch
+"""
+
+import util
+
+
+class SearchProblem:
+    """
+    This class outlines the structure of a search problem, but doesn't implement
+    any of the methods (in object-oriented terminology: an abstract class).
+
+    You do not need to change anything in this class, ever.
+    """
+
+    def getStartState(self):
+        """
+        Returns the start state for the search problem.
+        """
+        util.raiseNotDefined()
+
+    def isGoalState(self, state):
+        """
+          state: Search state
+
+        Returns True if and only if the state is a valid goal state.
+        """
+        util.raiseNotDefined()
+
+    def getSuccessors(self, state):
+        """
+          state: Search state
+
+        For a given state, this should return a list of triples, (successor,
+        action, stepCost), where 'successor' is a successor to the current
+        state, 'action' is the action required to get there, and 'stepCost' is
+        the incremental cost of expanding to that successor.
+        """
+        util.raiseNotDefined()
+
+    def getCostOfActions(self, actions):
+        """
+         actions: A list of actions to take
+
+        This method returns the total cost of a particular sequence of actions.
+        The sequence must be composed of legal moves.
+        """
+        util.raiseNotDefined()
+
+
+def tinyMazeSearch(problem):
+    """
+    Returns a sequence of moves that solves tinyMaze.  For any other maze, the
+    sequence of moves will be incorrect, so only use this for tinyMaze.
+    """
+    from game import Directions
+    s = Directions.SOUTH
+    w = Directions.WEST
+    return [s, s, w, s, w, w, s, w]
+
+
+def depthFirstSearch(problem: SearchProblem):
+    """
+    Search the deepest nodes in the search tree first.
+
+    Your search algorithm needs to return a list of actions that reaches the
+    goal. Make sure to implement a graph search algorithm.
+
+    To get started, you might want to try some of these simple commands to
+    understand the search problem that is being passed in:
+
     print("Start:", problem.getStartState())
     print("Is the start a goal?", problem.isGoalState(problem.getStartState()))
     print("Start's successors:", problem.getSuccessors(problem.getStartState()))
     """
     "*** YOUR CODE HERE ***"
-    util.raiseNotDefined()
+    fringe = Stack()
+    visited = set()
+
+    fringe.push((problem.getStartState(), []))
+
+    while not fringe.isEmpty():
+        node, path = fringe.pop()
+        if problem.isGoalState(node):
+            return path
+
+        if node not in visited:
+            visited.add(node)
+            for successor in problem.getSuccessors(node):
+                fringe.push((successor[0], path + [successor[1]]))
+
+
 
 def breadthFirstSearch(problem):
     """Search the shallowest nodes in the search tree first."""
     "*** YOUR CODE HERE ***"
-    util.raiseNotDefined()
+    from game import Directions, Actions
+
+    queue = util.Queue()
+    visited = set()
+    actions = []
+    # print(queue.isEmpty())
+    print("Start:", problem.getStartState())
+    print("Is the start a goal?", problem.isGoalState(problem.getStartState()))
+    print("Start's successors:", problem.getSuccessors(problem.getStartState()))
+
+    # push root (starting position)
+    root = problem.getStartState()
+    queue.push(root)
+
+    visited.add(root)
+    while not queue.isEmpty():
+        current_node = queue.pop()
+        print("Visiting:", current_node)
+
+        if (problem.isGoalState(current_node)):
+            print("Reached the goal")
+            break
+
+        for paths in problem.getSuccessors(current_node):
+            path = paths[0]
+            if path not in visited:
+                visited.add(path)
+                queue.push(path)
+    print(actions)
+    return path
+
 
 def uniformCostSearch(problem):
     """Search the node of least total cost first."""