摘要：
Given a binary tree, return the preorder traversal of its nodes' values.For example: Given binary tree {1,#,2,3}, 1 \ 2 / 3return [1,2,3].Note: Recursive solution is trivial, could you do it iteratively?思考：不可以递归，那么用栈存储结点。先用递归法做，算是加深记忆。需要注意ret需要清空，不然会记录上一次测试用例，所以将先序遍历单独写出来。class Solutio... 阅读全文
摘要：
Sort a linked list using insertion sort.思考：画图帮助理解，考虑以下情况：空链表，单结点链表，两个结点（第二个结点大于或小于第一个），多个结点。/** * Definition for singly-linked list. * struct ListNode { * int val; * ListNode *next; * ListNode(int x) : val(x), next(NULL) {} * }; */class Solution {public: ListNode *insertionSortList(Li... 阅读全文
摘要：
Implement strStr().Returns a pointer to the first occurrence of needle in haystack, or null if needle is not part of haystack.思考：复习KMP算法。class Solution {public: char *strStr(char *haystack, char *needle) { // IMPORTANT: Please reset any member data you declared, as // the same Solut... 阅读全文