Tree of Thoughts Implementation

Hard
Agents

Implement Tree of Thoughts (ToT) reasoning:

ToT Framework: Instead of linear reasoning (CoT), explore multiple reasoning paths as a tree.

Components:

  1. generate_thoughts(state, k): Generate k candidate next steps
  2. evaluate_state(state): Score state (0-1)
  3. search(initial, goal_test, strategy): Find solution path
    • bfs: Breadth-first exploration
    • dfs: Depth-first
    • beam: Keep only top-k branches at each level
  4. prune_low_value_branches(threshold): Remove poor branches
  5. backtrack_best_path(): Extract solution

Node Structure: {'state': ..., 'parent': ..., 'children': [...], 'value': ..., 'depth': ...}

Search: Explore tree, evaluating states, pruning low-value branches.

Examples

Example 1:
Input: tot = TreeOfThoughts(branching_factor=2, max_depth=3); thoughts = tot.generate_thoughts('start', 2); len(thoughts)
Output: 2
Explanation: Generated 2 thoughts as requested

Starter Code

class TreeOfThoughts:
    """
    Tree of Thoughts reasoning for complex problem solving.
    """
    
    def __init__(self, branching_factor=3, max_depth=5):
        self.branching_factor = branching_factor
        self.max_depth = max_depth
        self.tree = {}
    
    def generate_thoughts(self, state, k):
        """Generate k possible next thoughts from state"""
        # Your implementation here
        pass
    
    def evaluate_state(self, state):
        """
        Evaluate state value (0-1).
        Higher = more promising for reaching goal.
        """
        # Your implementation here
        pass
    
    def search(self, initial_state, goal_test, strategy='bfs'):
        """
        Search for solution using ToT.
        Strategies: 'bfs', 'dfs', 'beam'
        Returns path of thoughts to solution.
        """
        # Your implementation here
        pass
    
    def prune_low_value_branches(self, threshold=0.3):
        """Remove branches with value below threshold"""
        # Your implementation here
        pass
    
    def backtrack_best_path(self):
        """Find best path from root to leaf"""
        # Your implementation here
        pass
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