Merge 4ea6b46 into d31ec0a

algorithms/matrix/__init__.py

@@ -0,0 +1 @@
+

algorithms/tree/bin_tree_to_list.py

@@ -1,8 +1,5 @@
-class Node():
-    def __init__(self, val = 0):
-        self.val = val
-        self.left = None
-        self.right = None
+from tree.tree import TreeNode
+
 
 def bin_tree_to_list(root):
     """
@@ -15,6 +12,7 @@ def bin_tree_to_list(root):
         root = root.left
     return root
 
+
 def bin_tree_to_list_util(root):
     if not root:
         return root
@@ -32,18 +30,8 @@ def bin_tree_to_list_util(root):
         root.right = right
     return root
 
+
 def print_tree(root):
     while root:
         print(root.val)
         root = root.right
-
-tree = Node(10)
-tree.left = Node(12)
-tree.right = Node(15)
-tree.left.left  = Node(25)
-tree.left.left.right  = Node(100)
-tree.left.right = Node(30)
-tree.right.left = Node(36)
-
-head = bin_tree_to_list(tree)
-print_tree(head)

algorithms/tree/binary_tree_paths.py

@@ -1,12 +1,13 @@
 def binary_tree_paths(root):
     res = []
-    if not root:
+    if root is None:
         return res
     dfs(res, root, str(root.val))
     return res
 
+
 def dfs(res, root, cur):
-    if not root.left and not root.right:
+    if root.left is None and root.right is None:
         res.append(cur)
     if root.left:
         dfs(res, root.left, cur+'->'+str(root.left.val))

algorithms/tree/deepest_left.py

@@ -12,18 +12,15 @@
             # 7
 # should return 4.
 
+from tree.tree import TreeNode
 
-class Node:
-    def __init__(self, val = None):
-        self.left = None
-        self.right = None
-        self.val = val
 
 class DeepestLeft:
     def __init__(self):
         self.depth = 0
         self.Node = None
 
+
 def find_deepest_left(root, is_left, depth, res):
     if not root:
         return
@@ -33,15 +30,17 @@ def find_deepest_left(root, is_left, depth, res):
     find_deepest_left(root.left, True, depth + 1, res)
     find_deepest_left(root.right, False, depth + 1, res)
 
-root = Node(1)
-root.left = Node(2)
-root.right = Node(3)
-root.left.left = Node(4)
-root.left.right = Node(5)
-root.right.right = Node(6)
-root.right.right.right = Node(7)
-
-res = DeepestLeft()
-find_deepest_left(root, True, 1, res)
-if res.Node:
-    print(res.Node.val)
+
+if __name__ == '__main__':
+    root = TreeNode(1)
+    root.left = TreeNode(2)
+    root.right = TreeNode(3)
+    root.left.left = TreeNode(4)
+    root.left.right = TreeNode(5)
+    root.right.right = TreeNode(6)
+    root.right.right.right = TreeNode(7)
+
+    res = DeepestLeft()
+    find_deepest_left(root, True, 1, res)
+    if res.Node:
+        print(res.Node.val)

algorithms/tree/invert_tree.py

@@ -1,7 +1,7 @@
 # invert a binary tree
 
 def reverse(root):
-    if not root:
+    if root is None:
         return
     root.left, root.right = root.right, root.left
     if root.left:

algorithms/tree/is_balanced.py

@@ -1,33 +1,36 @@
-
 def is_balanced(root):
+    return __is_balanced_recursive(root)
+
+
+def __is_balanced_recursive(root):
     """
     O(N) solution
     """
-    return -1 != get_depth(root)
+    return -1 != __get_depth(root)
+
 
-def get_depth(root):
+def __get_depth(root):
     """
     return 0 if unbalanced else depth + 1
     """
-    if not root:
+    if root is None:
         return 0
-    left  = get_depth(root.left)
-    right = get_depth(root.right)
-    if abs(left-right) > 1 or left == -1 or right == -1:
+    left  = __get_depth(root.left)
+    right = __get_depth(root.right)
+    if abs(left-right) > 1 or -1 in [left, right]:
         return -1
     return 1 + max(left, right)
 
-################################
 
-def is_balanced(root):
-    """
-    O(N^2) solution
-    """
-    left = max_height(root.left)
-    right = max_height(root.right)
-    return abs(left-right) <= 1 and is_balanced(root.left) and is_balanced(root.right)
+# def is_balanced(root):
+#     """
+#     O(N^2) solution
+#     """
+#     left = max_height(root.left)
+#     right = max_height(root.right)
+#     return abs(left-right) <= 1 and is_balanced(root.left) and is_balanced(root.right)
 
-def max_height(root):
-    if not root:
-        return 0
-    return max(max_height(root.left), max_height(root.right)) + 1
+# def max_height(root):
+#     if root is None:
+#         return 0
+#     return max(max_height(root.left), max_height(root.right)) + 1

algorithms/tree/is_subtree.py

@@ -64,10 +64,8 @@ def is_subtree(big, small):
 
 
 def comp(p, q):
-    if not p and not q:
+    if p is None and q is None:
         return True
-    if p and q:
+    if p is not None and q is not None:
         return p.val == q.val and comp(p.left,q.left) and comp(p.right, q.right)
     return False
-
-

algorithms/tree/is_symmetric.py

@@ -21,28 +21,28 @@
 
 # TC: O(b) SC: O(log n)
 def is_symmetric(root):
-    if not root:
+    if root is None:
         return True
     return helper(root.left, root.right)
 
 
 def helper(p, q):
-    if not p and not q:
+    if p is None and q is None:
         return True
-    if not p or not q or q.val != p.val:
+    if p is not None or q is not None or q.val != p.val:
         return False
     return helper(p.left, q.right) and helper(p.right, q.left)
 
 
 def is_symmetric_iterative(root):
-    if not root:
+    if root is None:
         return True
     stack = [[root.left, root.right]]
     while stack:
         left, right = stack.pop()  # popleft
-        if not left and not right:
+        if left is None and right is None:
             continue
-        if not left or not right:
+        if left is None or right is None:
             return False
         if left.val == right.val:
             stack.append([left.left, right.right])

algorithms/tree/longest_consecutive.py

@@ -30,15 +30,15 @@ def longest_consecutive(root):
     :type root: TreeNode
     :rtype: int
     """
-    if not root:
+    if root is None:
         return 0
     max_len = 0
     dfs(root, 0, root.val, max_len)
     return max_len
 
 
 def dfs(root, cur, target, max_len):
-    if not root:
+    if root is None:
         return
     if root.val == target:
         cur += 1

algorithms/tree/lowest_common_ancestor.py

@@ -28,10 +28,10 @@ def lca(root, p, q):
     :type q: TreeNode
     :rtype: TreeNode
     """
-    if not root or root is p or root is q:
+    if root is None or root is p or root is q:
         return root
     left = lca(root.left, p, q)
     right = lca(root.right, p, q)
-    if left and right:
+    if left is not None and right is not None:
         return root
     return left if left else right

algorithms/tree/max_height.py

@@ -5,21 +5,18 @@
 longest path from the root node down to the farthest leaf node.
 """
 
-
-class Node():
-    def __init__(self, val = 0):
-        self.val = val
-        self.left = None
-        self.right = None
-
 # def max_height(root):
-    # if not root:
-        # return 0
-    # return max(maxDepth(root.left), maxDepth(root.right)) + 1
+#     if not root:
+#         return 0
+#     return max(maxDepth(root.left), maxDepth(root.right)) + 1
 
 # iterative
+
+from tree.tree import TreeNode
+
+
 def max_height(root):
-    if not root:
+    if root is None:
         return 0
     height = 0
     queue = [root]
@@ -28,27 +25,30 @@ def max_height(root):
         level = []
         while queue:
             node = queue.pop(0)
-            if node.left:
+            if node.left is not None:
                 level.append(node.left)
-            if node.right:
+            if node.right is not None:
                 level.append(node.right)
         queue = level
     return height
 
+
 def print_tree(root):
-    if root:
+    if root is not None:
         print(root.val)
         print_tree(root.left)
         print_tree(root.right)
 
-tree = Node(10)
-tree.left = Node(12)
-tree.right = Node(15)
-tree.left.left  = Node(25)
-tree.left.left.right  = Node(100)
-tree.left.right = Node(30)
-tree.right.left = Node(36)
-
-height = max_height(tree)
-print_tree(tree)
-print("height:", height)
+
+if __name__ == '__main__':
+    tree = TreeNode(10)
+    tree.left = TreeNode(12)
+    tree.right = TreeNode(15)
+    tree.left.left = TreeNode(25)
+    tree.left.left.right = TreeNode(100)
+    tree.left.right = TreeNode(30)
+    tree.right.left = TreeNode(36)
+
+    height = max_height(tree)
+    print_tree(tree)
+    print("height:", height)

algorithms/tree/max_path_sum.py

@@ -1,13 +1,11 @@
-
-
 def max_path_sum(root):
     maximum = float("-inf")
     helper(root, maximum)
     return maximum
 
 
 def helper(root, maximum):
-    if not root:
+    if root is None:
         return 0
     left = helper(root.left, maximum)
     right = helper(root.right, maximum)