[Binary Tree] Different views of binary tree added

data_structures/binary_tree/diff_views_of_binary_tree.py

@@ -0,0 +1,195 @@
+"""
+Problem:
+Given root of binary Tree, print the
+
+1. binary-tree-right-side-view
+2. binary-tree-left-side-view
+3. binary-tree-top-side-view
+4. binary-tree-bottom-side-view
+
+
+1. binary-tree-right-side-view
+
+    3       <-  3
+   / \
+  9   20    <-  20
+     /  \
+    15   7  <-  7
+
+Output: [3, 20, 7]
+
+
+2. binary-tree-left-side-view
+
+3  ->    3
+        / \
+9  ->  9   20
+          /  \
+15 ->    15   7
+
+Output: [3, 9, 15]
+
+
+3. binary-tree-top-side-view
+
+  9 3 20 7
+  ⬇ ⬇ ⬇  ⬇
+
+    3
+   / \
+  9   20
+     /  \
+    15   7
+
+Output: [9, 3, 20, 7]
+
+4. binary-tree-bottom-side-view
+
+    3
+   / \
+  9   20
+     /  \
+    15   7
+  ↑  ↑ ↑  ↑
+  9 15 20 7
+
+Output: [9, 15, 20, 7]
+
+"""
+
+from __future__ import annotations
+
+class TreeNode:
+    def __init__(
+        self, val: int = 0, left: TreeNode | None = None, right: TreeNode | None = None
+    ) -> None:
+        self.val = val
+        self.left = left
+        self.right = right
+
+def binary_tree_right_side_view(root: TreeNode | None) -> list[int]:
+    """
+    Function returns the right side view of binary tree.
+
+    >>> binary_tree_right_side_view(None)
+    []
+    """
+    def dfs(root: TreeNode | None, depth: int, right_view: list[int]) -> None:
+        if not root:
+            return
+
+        if depth == len(right_view):
+            right_view.append(root.val)
+
+        dfs(root.right, depth + 1, right_view)
+        dfs(root.left, depth + 1, right_view)
+
+    right_view = []
+    if not root:
+        return right_view
+    dfs(root, 0, right_view)
+    return right_view
+
+def binary_tree_left_side_view(root: TreeNode | None) -> list[int]:
+    """
+    Function returns the left side view of binary tree.
+
+    >>> binary_tree_left_side_view(None)
+    []
+    """
+    def dfs(root: TreeNode | None, depth: int, left_view: list[int]) -> None:
+        if not root:
+            return
+
+        if depth == len(left_view):
+            left_view.append(root.val)
+
+        dfs(root.left, depth + 1, left_view)
+        dfs(root.right, depth + 1, left_view)
+
+    left_view = []
+    if not root:
+        return left_view
+    dfs(root, 0, left_view)
+    return left_view
+
+def binary_tree_top_side_view(root: TreeNode | None) -> list[int]:
+    """
+    Function returns the top side view of binary tree.
+
+    >>> binary_tree_top_side_view(None)
+    []
+    """
+    from collections import defaultdict
+
+    def bfs(root: TreeNode | None, top_view: list[int]) -> None:
+        queue = [(root, 0)]
+        lookup = defaultdict(list)
+
+        while queue:
+            first = queue.pop(0)
+            node,hd = first
+            lookup[hd].append(node.val)
+
+            if node.left:
+                queue.append((node.left, hd - 1))
+            if node.right:
+                queue.append((node.right, hd + 1))
+
+        for key, val in sorted(lookup.items(), key = lambda x:x[0]):
+            top_view.append(val[0])
+
+    top_view = []
+    if not root:
+        return top_view
+    bfs(root, top_view)
+    return top_view
+
+def binary_tree_bottom_side_view(root: TreeNode | None) -> list[int]:
+    """
+    Function returns the bottom side view of binary tree
+
+    >>> binary_tree_bottom_side_view(None)
+    []
+    """
+    from collections import defaultdict
+
+    def bfs(root: TreeNode | None, bottom_view: list[int]) -> None:
+        queue = [(root, 0)]
+        lookup = defaultdict(list)
+
+        while queue:
+            first = queue.pop(0)
+            node,hd = first
+            lookup[hd].append(node.val)
+
+            if node.left:
+                queue.append((node.left, hd - 1))
+            if node.right:
+                queue.append((node.right, hd + 1))
+
+        for key, val in sorted(lookup.items(), key = lambda x:x[0]):
+            bottom_view.append(val[-1])
+
+    bottom_view = []
+    if not root:
+        return bottom_view
+    bfs(root, bottom_view)
+    return bottom_view
+
+
+tree_1 = TreeNode(3)
+tree_1.left = TreeNode(9)
+tree_1.right = TreeNode(20)
+tree_1.right.left = TreeNode(15)
+tree_1.right.right = TreeNode(7)
+
+print(binary_tree_right_side_view(tree_1))  # Output: [3, 20, 7]
+print(binary_tree_left_side_view(tree_1))   # Output: [3, 9, 15]
+print(binary_tree_top_side_view(tree_1))    # Output: [9, 3, 20, 7]
+print(binary_tree_bottom_side_view(tree_1)) # Output: [9, 15, 20, 7]
+
+if __name__ == "__main__":
+    import doctest
+
+    doctest.testmod()