百草园

摘要： Sort a linked list inO(nlogn) time using constant space complexity.归并排序！用慢指针、快指针来寻找二分位置，这里很容易出现错，要特别注意。 1 /** 2 * Definition for singly-linked list. 3 * struct ListNode { 4 * int val; 5 * ListNode *next; 6 * ListNode(int x) : val(x), next(NULL) {} 7 * }; 8 */ 9 class Solution {10 ... 阅读全文

摘要： Design and implement a data structure for Least Recently Used (LRU) cache. It should support the following operations:getandset.get(key)- Get the valu... 阅读全文

摘要： Given a linked list, return the node where the cycle begins. If there is no cycle, returnnull.Follow up:Can you solve it without using extra space?转自:http://www.cnblogs.com/x1957/p/3406448.html比I麻烦点的就是找到循环开始点TATI只是判断是否循环。要求不使用额外空间（不然hash就可以了按I的思路，我们又慢指针S和快指针F。。。F走两步，S走一步。。。若有环，必定相遇。画个图（很丑勿喷假设在红色凸起的地 阅读全文

摘要： Givennpairs of parentheses, write a function to generate all combinations of well-formed parentheses.For example, givenn= 3, a solution set is:"((()))", "(()())", "(())()", "()(())", "()()()"递归与深搜。 1 class Solution { 2 public: 3 void getRes(vector &a 阅读全文

摘要： You are given annxn2D matrix representing an image.Rotate the image by 90 degrees (clockwise).Follow up:Could you do this in-place?用了最笨的办法。就地转的话应该是一圈一... 阅读全文

摘要： A message containing letters fromA-Zis being encoded to numbers using the following mapping:'A' -> 1'B' -> 2...'Z' -> 26Given an encoded message containing digits, determine the total number of ways to decode it.For example,Given encoded message"12", it cou 阅读全文

摘要： 题目描述：数组中有一个数字出现的次数超过数组长度的一半，请找出这个数字。例如输入一个长度为9的数组{1,2,3,2,2,2,5,4,2}。由于数字2在数组中出现了5次，超过数组长度的一半，因此输出2。输入：每个测试案例包括2行：第一行输入一个整数n（1 2 #include 3 using namespace std; 4 5 int main() 6 { 7 int n; 8 long a[100005]; 9 10 while (cin >> n) {11 for (int i=0; i > a[i];13 }14 ... 阅读全文

摘要： Given a 2D board and a word, find if the word exists in the grid.The word can be constructed from letters of sequentially adjacent cell, where "adjace... 阅读全文

摘要： The count-and-say sequence is the sequence of integers beginning as follows:1, 11, 21, 1211, 111221, ...1is read off as"one 1"or11.11is read off as"two 1s"or21.21is read off as"one 2, thenone 1"or1211.Given an integern, generate thenthsequence.Note: The sequence of inte 阅读全文

摘要： Given amxnmatrix, if an element is 0, set its entire row and column to 0. Do it in place.如果不用额外空间的话，可以把第一行与第一列作为标记行与标记列，但是得先确定第一行与第一列本身要不要设为0。 1 class Solution { 2 public: 3 void setZeroes(vector > &matrix) { 4 if (matrix.size() < 1) return; 5 int row = matrix.size(), col = matri... 阅读全文