Initial Commit of Chapter 3; Added Headers to all Source Files

davecom · davecom · commit f8c74d9bf5ed · 2018-06-13T22:09:56.000-04:00
diff --git a/Chapter1/calculating_pi.py b/Chapter1/calculating_pi.py
@@ -1,3 +1,18 @@
+# calculating_pi.py
+# From Classic Computer Science Problems in Python Chapter 1
+# Copyright 2018 David Kopec
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+# http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
 def calculate_pi(n_terms: int) -> float:
     numerator: float = 4.0
     denominator: float = 1.0
diff --git a/Chapter1/fib1.py b/Chapter1/fib1.py
@@ -1,6 +1,22 @@
+# fib1.py
+# From Classic Computer Science Problems in Python Chapter 1
+# Copyright 2018 David Kopec
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+# http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
 def fib1(n: int) -> int:
     return fib1(n - 1) + fib1(n - 2)
 
 
 if __name__ == "__main__":
     print(fib1(5))
+# Note that this example is purposefully wrong.
diff --git a/Chapter1/fib2.py b/Chapter1/fib2.py
@@ -1,3 +1,18 @@
+# fib2.py
+# From Classic Computer Science Problems in Python Chapter 1
+# Copyright 2018 David Kopec
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+# http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
 def fib2(n: int) -> int:
     if n < 2:  # base case
         return n
diff --git a/Chapter1/fib3.py b/Chapter1/fib3.py
@@ -1,3 +1,18 @@
+# fib3.py
+# From Classic Computer Science Problems in Python Chapter 1
+# Copyright 2018 David Kopec
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+# http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
 from typing import Dict
 memo: Dict[int, int] = {0: 0, 1: 1}  # our old base cases
 
diff --git a/Chapter1/fib4.py b/Chapter1/fib4.py
@@ -1,3 +1,18 @@
+# fib4.py
+# From Classic Computer Science Problems in Python Chapter 1
+# Copyright 2018 David Kopec
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+# http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
 from functools import lru_cache
 
 
diff --git a/Chapter1/fib5.py b/Chapter1/fib5.py
@@ -1,3 +1,18 @@
+# fib5.py
+# From Classic Computer Science Problems in Python Chapter 1
+# Copyright 2018 David Kopec
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+# http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
 def fib5(n: int) -> int:
     if n == 0: return n  # special case
     last: int = 0  # initially set to fib(0)
diff --git a/Chapter1/fib6.py b/Chapter1/fib6.py
@@ -1,3 +1,18 @@
+# fib6.py
+# From Classic Computer Science Problems in Python Chapter 1
+# Copyright 2018 David Kopec
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+# http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
 def fib6(n: int) -> int:
     yield 0  # special case
     if n > 0: yield 1  # special case
diff --git a/Chapter1/hanoi.py b/Chapter1/hanoi.py
@@ -1,3 +1,18 @@
+# hanoi.py
+# From Classic Computer Science Problems in Python Chapter 1
+# Copyright 2018 David Kopec
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+# http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
 from typing import TypeVar, Generic, List
 T = TypeVar('T')
 
diff --git a/Chapter1/trivial_compression.py b/Chapter1/trivial_compression.py
@@ -1,3 +1,18 @@
+# trivial_compression.py
+# From Classic Computer Science Problems in Python Chapter 1
+# Copyright 2018 David Kopec
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+# http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
 class CompressedGene:
     def __init__(self, gene: str):
         self._compress(gene)
diff --git a/Chapter1/unbreakable_encryption.py b/Chapter1/unbreakable_encryption.py
@@ -1,3 +1,18 @@
+# unbreakable_encryption.py
+# From Classic Computer Science Problems in Python Chapter 1
+# Copyright 2018 David Kopec
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+# http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
 from secrets import token_bytes
 
 
diff --git a/Chapter2/dna_search.py b/Chapter2/dna_search.py
@@ -1,3 +1,18 @@
+# dna_search.py
+# From Classic Computer Science Problems in Python Chapter 2
+# Copyright 2018 David Kopec
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+# http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
 from enum import IntEnum
 from typing import Tuple, List
 
diff --git a/Chapter2/generic_search.py b/Chapter2/generic_search.py
@@ -1,3 +1,18 @@
+# generic_search.py
+# From Classic Computer Science Problems in Python Chapter 2
+# Copyright 2018 David Kopec
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+# http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
 from typing import TypeVar, Iterable, Sequence, Generic, List, Callable, Set, Deque, Dict, Any, Optional
 from typing_extensions import Protocol
 from functools import total_ordering
diff --git a/Chapter2/maze.py b/Chapter2/maze.py
@@ -1,3 +1,18 @@
+# maze.py
+# From Classic Computer Science Problems in Python Chapter 2
+# Copyright 2018 David Kopec
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+# http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
 from enum import Enum
 from typing import List, NamedTuple, Callable, Optional
 import random
diff --git a/Chapter2/missionaries.py b/Chapter2/missionaries.py
@@ -1,3 +1,18 @@
+# missionaries.py
+# From Classic Computer Science Problems in Python Chapter 2
+# Copyright 2018 David Kopec
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+# http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
 from typing import List, Optional
 from generic_search import bfs, Node, node_to_path
 
diff --git a/Chapter3/csp.py b/Chapter3/csp.py
@@ -0,0 +1,80 @@
+# csp.py
+# From Classic Computer Science Problems in Python Chapter 3
+# Copyright 2018 David Kopec
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+# http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+from typing import Generic, TypeVar, Dict, List, Optional
+from abc import ABC, abstractmethod
+
+V = TypeVar('V') # variable type
+D = TypeVar('D') # domain type
+
+
+# Base class for all constraints
+class Constraint(Generic[V, D], ABC):
+    # The variables that the constraint is between
+    def __init__(self, variables: List[V]) -> None:
+        self.variables = variables
+
+    # Must be overridden by subclasses
+    @abstractmethod
+    def satisfied(self, assignment: Dict[V, D]) -> bool:
+        ...
+
+
+# A constraint satisfaction problem consists of variables of type V
+# that have ranges of values known as domains of type D and constraints
+# that determine whether a particular variable's domain selection is valid
+class CSP(Generic[V, D]):
+    def __init__(self, variables: List[V], domains: Dict[V, List[D]]) -> None:
+        self.variables: List[V] = variables # variables to be constrained
+        self.domains: Dict[V, List[D]] = domains # domain of each variable
+        self.constraints: Dict[V, List[Constraint[V, D]]] = {}
+        for variable in self.variables:
+            self.constraints[variable] = []
+            if variable not in self.domains:
+                raise LookupError("Every variable should have a domain assigned to it.")
+
+    def add_constraint(self, constraint: Constraint[V, D]) -> None:
+        for variable in constraint.variables:
+            if variable not in self.variables:
+                raise LookupError("Variable in constraint not in CSP")
+            else:
+                self.constraints[variable].append(constraint)
+
+    def consistent(self, variable: V, assignment: Dict[V, D]) -> bool:
+        for constraint in self.constraints[variable]:
+            if not constraint.satisfied(assignment):
+                return False
+        return True
+
+    def backtracking_search(self, assignment: Dict[V, D] = {}) -> Optional[Dict[V, D]]:
+        # assignment is complete if every variable is assigned (our base case)
+        if len(assignment) == len(self.variables):
+            return assignment
+
+        # get all variables in the CSP but not in the assignment
+        unassigned: List[V] = [v for v in self.variables if v not in assignment]
+
+        # get the every possible domain value of the first unassigned variable
+        first: V = unassigned[0]
+        for value in self.domains[first]:
+            local_assignment = assignment.copy()
+            local_assignment[first] = value
+            # if we're still consistent, we recurse (continue)
+            if self.consistent(first, local_assignment):
+                result: Optional[Dict[V, D]] = self.backtracking_search(local_assignment)
+                # if we didn't find the result, we will end up backtracking
+                if result is not None:
+                    return result
+        return None
diff --git a/Chapter3/map_coloring.py b/Chapter3/map_coloring.py
diff --git a/Chapter3/queens.py b/Chapter3/queens.py
diff --git a/Chapter3/send_more_money.py b/Chapter3/send_more_money.py
diff --git a/Chapter3/word_search.py b/Chapter3/word_search.py
