algorithm010
diff --git a/‎Week03/code.js‎
Lines changed: 25 additions & 0 deletions b/‎Week03/code.js‎
Lines changed: 25 additions & 0 deletions
diff --git a/‎Week03/新建笔记.png‎
336 KB b/‎Week03/新建笔记.png‎
336 KB
@@ -0,0 +1,25 @@
+// 从前序与中序遍历序列构造二叉树
+var buildTree = function(preorder, inorder) {
+    if(!preorder.length) return null
+    const node = new TreeNode(preorder[0])
+    const index = inorder.indexOf(preorder[0])
+    const inLeft = inorder.slice(0, index)
+    const inRight = inorder.slice(index + 1)
+    const preLeft = preorder.slice(1, index + 1)
+    const preRight = preorder.slice(index + 1)
+    node.left = buildTree(preLeft, inLeft)
+    node.right = buildTree(preRight, inRight)
+    return node
+};
+
+
+// 二叉树的最近公共祖先
+var lowestCommonAncestor = function(root, p, q) {
+    if (root === null) return null
+    if (root == p || root == q) return root;
+    let left = lowestCommonAncestor(root.left, p , q)
+    let right = lowestCommonAncestor(root.right, p , q)
+    if (!left) return right;
+    if (!right) return left;
+    return root;
+};