diff --git a/problems/0108.将有序数组转换为二叉搜索树.md b/problems/0108.将有序数组转换为二叉搜索树.md index b8861b24..87b11ed4 100644 --- a/problems/0108.将有序数组转换为二叉搜索树.md +++ b/problems/0108.将有序数组转换为二叉搜索树.md @@ -209,6 +209,8 @@ public: Java: + +递归: 左闭右开 [left,right) ```Java class Solution { public TreeNode sortedArrayToBST(int[] nums) { @@ -232,6 +234,75 @@ class Solution { ``` +递归: 左闭右闭 [left,right] +```java +class Solution { + public TreeNode sortedArrayToBST(int[] nums) { + TreeNode root = traversal(nums, 0, nums.length - 1); + return root; + } + + // 左闭右闭区间[left, right) + private TreeNode traversal(int[] nums, int left, int right) { + if (left > right) return null; + + int mid = left + ((right - left) >> 1); + TreeNode root = new TreeNode(nums[mid]); + root.left = traversal(nums, left, mid - 1); + root.right = traversal(nums, mid + 1, right); + return root; + } +} +``` +迭代: 左闭右闭 [left,right] +```java +class Solution { + public TreeNode sortedArrayToBST(int[] nums) { + if (nums.length == 0) return null; + + //根节点初始化 + TreeNode root = new TreeNode(-1); + Queue nodeQueue = new LinkedList<>(); + Queue leftQueue = new LinkedList<>(); + Queue rightQueue = new LinkedList<>(); + + // 根节点入队列 + nodeQueue.offer(root); + // 0为左区间下表初始位置 + leftQueue.offer(0); + // nums.size() - 1为右区间下表初始位置 + rightQueue.offer(nums.length - 1); + + while (!nodeQueue.isEmpty()) { + TreeNode currNode = nodeQueue.poll(); + int left = leftQueue.poll(); + int right = rightQueue.poll(); + int mid = left + ((right - left) >> 1); + + // 将mid对应的元素给中间节点 + currNode.val = nums[mid]; + + // 处理左区间 + if (left <= mid - 1) { + currNode.left = new TreeNode(-1); + nodeQueue.offer(currNode.left); + leftQueue.offer(left); + rightQueue.offer(mid - 1); + } + + // 处理右区间 + if (right >= mid + 1) { + currNode.right = new TreeNode(-1); + nodeQueue.offer(currNode.right); + leftQueue.offer(mid + 1); + rightQueue.offer(right); + } + } + return root; + } +} +``` + Python: ```python3 # Definition for a binary tree node.