摘要：
Q:给定一个已排序的数组，将它转换成一个平衡的二叉查找树。A：Divide and conquer。为了达到一个平衡的二叉树，数组的中间元素做为root，然后对数组的左右两个部分分别生成新的子树，分别作为root的左右孩子。时间复杂度：O(n)空间复杂度：无额外开销 TreeNode *buildTree(vector<int> &num,int begin,int end) { if(begin<=end) { int middle = begin + (end - begin)/2; TreeNode *r... 阅读全文
摘要：
Q：Given a binary tree containing digits from0-9only, each root-to-leaf path could represent a number.An example is the root-to-leaf path1->2->3which represents the number123.Find the total sum of all root-to-leaf numbers.For example, 1 / \ 2 3The root-to-leaf path1->2represents the number12 阅读全文