maximum-depth-of-binary-tree solution (py, ts)

Author: hi-rachel

maximum-depth-of-binary-tree/hi-rachel.py

@@ -0,0 +1,44 @@
+# O(n) time, 모든 노드를 한 번씩 방문
+# O(h) for DFS / O(w) for BFS space, DFS는 재귀 호출 깊이 (h = 트리 높이), BFS는 큐에 들어가는 최대 노드 수 (w = 최대 너비)
+
+# Definition for a binary tree node.
+# class TreeNode:
+#     def __init__(self, val=0, left=None, right=None):
+#         self.val = val
+#         self.left = left
+#         self.right = right
+
+
+class TreeNode:
+    def __init__(self, val=0, left=None, right=None):
+        self.val = val
+        self.left = left
+        self.right = right
+
+# BFS 풀이
+from collections import deque
+
+class Solution:
+    def maxDepth(self, root: Optional[TreeNode]) -> int:
+        if not root:
+            return 0
+
+        queue = deque([root])
+        depth = 0
+
+        while queue:
+            for _ in range(len(queue)):
+                node = queue.popleft()
+                if node.left:
+                    queue.append(node.left)
+                if node.right:
+                    queue.append(node.right)
+            depth += 1
+        return depth
+
+# DFS 풀이
+class Solution:
+    def maxDepth(self, root: Optional[TreeNode]) -> int:
+        if not root:
+            return 0
+        return 1 + max(self.maxDepth(root.left), self.maxDepth(root.right))

maximum-depth-of-binary-tree/hi-rachel.ts

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+/**
+ * Definition for a binary tree node.
+ * class TreeNode {
+ *     val: number
+ *     left: TreeNode | null
+ *     right: TreeNode | null
+ *     constructor(val?: number, left?: TreeNode | null, right?: TreeNode | null) {
+ *         this.val = (val===undefined ? 0 : val)
+ *         this.left = (left===undefined ? null : left)
+ *         this.right = (right===undefined ? null : right)
+ *     }
+ * }
+ */
+
+// O(n) time, 모든 노드를 한 번씩 방문
+// O(h) for DFS / O(w) for BFS space, DFS는 재귀 호출 깊이 (h = 트리 높이), BFS는 큐에 들어가는 최대 노드 수 (w = 최대 너비)
+
+class TreeNode {
+  val: number;
+  left: TreeNode | null;
+  right: TreeNode | null;
+  constructor(val?: number, left?: TreeNode | null, right?: TreeNode | null) {
+    this.val = val === undefined ? 0 : val;
+    this.left = left === undefined ? null : left;
+    this.right = right === undefined ? null : right;
+  }
+}
+
+// BFS 풀이
+function maxDepth(root: TreeNode | null): number {
+  if (root === null) return 0;
+
+  const queue: TreeNode[] = [root];
+  let depth = 0;
+
+  while (queue.length > 0) {
+    const levelSize = queue.length;
+
+    for (let i = 0; i < levelSize; i++) {
+      const node = queue.shift();
+      if (node) {
+        if (node.left) queue.push(node.left);
+        if (node.right) queue.push(node.right);
+      }
+    }
+    depth++;
+  }
+  return depth;
+}
+
+// DFS 풀이
+// function maxDepth(root: TreeNode | null): number {
+//   if (root === null) return 0;
+//   const left = maxDepth(root.left);
+//   const right = maxDepth(root.right);
+//   return Math.max(left, right) + 1;
+// }