94. 二叉树的中序遍历 (二刷)

Author: w2xi

vs-lt/94.二叉树的中序遍历.js

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+/*
+ * @lc app=leetcode.cn id=94 lang=javascript
+ *
+ * [94] 二叉树的中序遍历
+ */
+
+// @lc code=start
+/**
+ * Definition for a binary tree node.
+ * function TreeNode(val, left, right) {
+ *     this.val = (val===undefined ? 0 : val)
+ *     this.left = (left===undefined ? null : left)
+ *     this.right = (right===undefined ? null : right)
+ * }
+ */
+/**
+ * @param {TreeNode} root
+ * @return {number[]}
+ */
+var inorderTraversal = function(root) {
+  const result = [];
+  const inOrder = (node) => {
+    if (node) {
+      inOrder(node.left);
+      result.push(node.val);
+      inOrder(node.right);
+    }
+  }
+  // inOrder(root);
+
+  // return result;
+
+  return inOrderIterate(root);
+};
+
+// 中序遍历
+// 左中右
+function inOrderIterate(root) {
+  const result = [];
+  const stack = [];
+  let curr = root;
+
+  while (stack.length || curr) {
+    while (curr) {
+      stack.push(curr);
+      curr = curr.left;
+    }
+    const node = stack.pop();
+    result.push(node.val);
+
+    if (node.right) {
+      curr = node.right;
+    }
+  }
+
+  return result;
+}
+// @lc code=end
+