add leetcode 104

Author: 子云

Week_01/id_39/LeetCode_104_39.js

@@ -0,0 +1,55 @@
+/**
+ * Definition for a binary tree node.
+ * function TreeNode(val) {
+ *     this.val = val;
+ *     this.left = this.right = null;
+ * }
+ */
+/**
+ * @param {TreeNode} root
+ * @return {number}
+ * https://leetcode.com/problems/maximum-depth-of-binary-tree/
+ */
+// 广度优先搜索
+var maxDepth = function(root) {
+    if (!root) {
+        return 0;
+    }
+
+    let queue = [];
+    let level = [root];
+    let depth = 0;
+
+    while (level.length) {
+        depth++;
+
+        while (level.length) {
+            let node = level.shift();
+            if (node.left) {
+                queue.push(node.left);
+            }
+            if (node.right) {
+                queue.push(node.right);
+            }
+        }
+        level = queue;
+        queue = [];
+    }
+
+    return depth;
+};
+
+// DFS 深度优先搜索 递归形式
+var maxDepth = function(root) {
+    if (!root) {
+        return 0;
+    }
+    return Math.max(maxDepth(root.left) + 1, maxDepth(root.right) + 1);
+};
+
+// DFS 深度优先搜索 非递归形式
+var maxDepth = function(root) {
+    if (!root) {
+        return 0;
+    }
+};