1. Maximum Depth of Binary Tree

Author: Sunjae95

maximum-depth-of-binary-tree/sunjae95.js

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+/**
+ * @description
+ * 최대 깊이를 탐색하는 문제여서 dfs를 먼저 떠올렸지만 이번에 bfs로 풀이하고 싶어 bfs로 풀었습니다.
+ *
+ * n = total node count
+ * time complexity: O(n)
+ * space complexity: O(n)
+ */
+var maxDepth = function (root) {
+  const queue = [];
+  let lastIndex = queue.length;
+  let answer = 0;
+
+  if (!root) return answer;
+
+  queue.push(root);
+
+  while (queue.length !== lastIndex) {
+    let currentCount = queue.length - lastIndex;
+    answer++;
+
+    while (currentCount--) {
+      let currentNode = queue[lastIndex];
+      lastIndex++;
+      if (currentNode.left) queue.push(currentNode.left);
+      if (currentNode.right) queue.push(currentNode.right);
+    }
+  }
+
+  return answer;
+};