摘要： 题目：Given a binary tree, find its maximum depth.The maximum depth is the number of nodes along the longest path from the root node down to the farthest leaf node.思路1：We can solve this easily using recursion. Why? Because each of the leftChild and rightChild of a node is a sub-tree itself. We first co 阅读全文

摘要： 题目：Follow up for N-Queens problem.Now, instead outputting board configurations, return the total number of distinct solutions.思路：与N queens 一样代码：class Solution {public: bool isOK(vector<int> oneSolution, int k, int val){ for (int i=0; i<k; i++){ if (oneSol... 阅读全文

摘要： 题目：You are climbing a stair case. It takesnsteps to reach to the top.Each time you can either climb 1 or 2 steps. In how many distinct ways can you climb to the top?思路： 此题可以由迭代或DP解决，在此贴一个 top down的DP代码：class Solution {public: int helper(int n, vector<int> &map){ if (n < 0) retu... 阅读全文