- 解题思路
- 根据树的前序遍历+中序遍历可确定一棵树
- 利用二分递归查找数组可得到所有子树的根节点
- 根据树的中序遍历+后序遍历可确定一棵树
- 根据树的前序遍历+中序遍历可确定一棵树
public TreeNode f (int[] nums) {
return helper(nums, 0, nums.length);
}
public TreeNode helper(int[] nums, int start, int end) {
if (start == end) return null;
int mid = (start + end) / 2;
TreeNode root = new TreeNode(nums[mid]);
root.left = helper(nums, start, mid); //此处始终选择中点作为左子树的根
root.right = helper(nums, mid + 1, end);
return root;
}