面试题16:反转链表 提交网址: http://www.nowcoder.com/practice/75e878df47f24fdc9dc3e400ec6058ca?tpId=13&tqId=11168 或 https://leetcode.com/problems/reverse-linked-list/ Total Accepted: 101523  Total Submissions: 258623  Difficulty: Easy Reverse a singly linked lis…

LeetCode:二叉树的锯齿形层次遍历[103] 题目描述 给定一个二叉树,返回其节点值的锯齿形层次遍历.(即先从左往右,再从右往左进行下一层遍历,以此类推,层与层之间交替进行). 例如:给定二叉树 [3,9,20,null,null,15,7], 3 / \ 9 20 / \ 15 7 返回锯齿形层次遍历如下: [ [3], [20,9], [15,7] ] 题目分析 层次遍历,应该很容易想到BFS(宽度优先搜索算法),此处是锯齿形,即一层是从左往右,下一层就是从右往左. 解决办法是每一层都…

堆栈基础 堆栈(stack)具有“后进先出”的特性,利用这个特性我们可以用堆栈来解决这样一类问题:后续的输入会影响到前面的阶段性结果.线性地遍历输入并用stack处理,这类问题较简单,求解时间复杂度一般为O(n). 相关LeetCode题: 13. Roman to Integer  题解 20. Valid Parentheses  题解 844. Backspace String Compare  题解 1047. Remove All Adjacent Duplicates In Stri…

链表基础 链表(Linked List)相比数组(Array),物理存储上非连续.不支持O(1)时间按索引存取:但链表也有其优点,灵活的内存管理.允许在链表任意位置上插入和删除节点.单向链表结构一般如下: //Definition for singly-linked list. struct ListNode { int val; ListNode *next; ListNode(int x) : val(x), next(NULL) {} }; 相关LeetCode题: 707. Design…

比赛链接:https://codeforces.com/contest/1437 A. Marketing Scheme 题解 令 \(l = \frac{a}{2}\),那么如果 \(r < a\),每个顾客都会买更多猫粮. 代码 #include <bits/stdc++.h> using namespace std; int main() { ios::sync_with_stdio(false); cin.tie(nullptr); int t; cin >> t;…

前言   [LeetCode 题解]系列传送门:  http://www.cnblogs.com/double-win/category/573499.html   1.题目描述 Given a linked list, reverse the nodes of a linked list k at a time and return its modified list. If the number of nodes is not a multiple of k then left-out no…

题目来源 https://leetcode.com/problems/reverse-linked-list-ii/ Reverse a linked list from position m to n. Do it in-place and in one-pass. For example:Given 1->2->3->4->5->NULL, m = 2 and n = 4, return 1->4->3->2->5->NULL. Note:G…

题目: 数字翻转,即输入123,返回321:输入-123,返回-321. 代码: class Solution { public: int reverse(int x) { , sign = ; ) //负数转换为正数统一处理 { x = -x; sign = -; } ) { result *= ; result += x % ; x /= ; } return result * sign; //返回时记得加上符号 } };…

problem: Reverse digits of an integer. Example1: x = 123, return 321 Example2: x = -123, return -321 thinking: (1)整型反转直观非常easy理解. 如正负,尾数为0等问题还优点理. (2)反转溢出问题要细致处理. code: class Solution { public: int reverse(int x) { long long int y=x; bool flag=true;…

题目: Given a 32-bit signed integer, reverse digits of an integer. Example 1: Input: 123 Output: 321 Example 2: Input: -123 Output: -321 Example 3: Input: 120 Output: 21 Note:Assume we are dealing with an environment which could only hold integers with…