Algorithm : 做一个 leetcode 的算法题
//二位数组查找 题目描述
//在一个二维数组中(每个一维数组的长度相同),每一行都按照从左到右递增的顺序排序,每一列都按照从上到下递增的顺序排序。
//请完成一个函数,输入这样的一个二维数组和一个整数,判断数组中是否含有该整数。
bool FindNum(int target, vector<vector<int> > vect) { int iRow = vect.size(); int iCol = vect[0].size(); //从左上角开始遍历 int i = 0, j = iCol - 1; while (i <= iRow - 1 && j >= 0) //保证数组不能越界 { if (vect[i][j] > target) { j--; } else if (vect[i][j] < target) { i++; } else { return true; } } return false; }
Review : 阅读并点评一篇英文技术文章
原文地址:http://download.redis.io/redis-stable/redis.conf
################################ SNAPSHOTTING ################################
#
# Save the DB on disk:
#
# save <seconds> <changes>
#
# Will save the DB if both the given number of seconds and the given
# number of write operations against the DB occurred.
根据给定的每秒多少写操作保存DB;
#
# In the example below the behaviour will be to save:
# after 900 sec (15 min) if at least 1 key changed
# after 300 sec (5 min) if at least 10 keys changed
# after 60 sec if at least 10000 keys changed
#
# Note: you can disable saving completely by commenting out all "save" lines.
#
# It is also possible to remove all the previously configured save
# points by adding a save directive with a single empty string argument
# like in the following example:
#
# save ""
save 900 1
save 300 10
save 60 10000
保存DB到磁盘:
# By default Redis will stop accepting writes if RDB snapshots are enabled
# (at least one save point) and the latest background save failed.
# This will make the user aware (in a hard way) that data is not persisting
# on disk properly, otherwise chances are that no one will notice and some
# disaster will happen.
默认情况下:如果开启了RDB快照(至少一个保存点)并且最后一个备份保存失败,那么redis将停止接受写操作;
#
# If the background saving process will start working again Redis will
# automatically allow writes again.
#
# However if you have setup your proper monitoring of the Redis server
# and persistence, you may want to disable this feature so that Redis will
# continue to work as usual even if there are problems with disk,
# permissions, and so forth.
stop-writes-on-bgsave-error yes
但是,如果你设置了对redis服务器和持久性的适当监控,你可能希望禁用这些特性以便即使存在硬盘、权限等问题,Redis也能照常工作!
# Compress string objects using LZF when dump .rdb databases?
# For default that‘s set to ‘yes‘ as it‘s almost always a win.
# If you want to save some CPU in the saving child set it to ‘no‘ but
# the dataset will likely be bigger if you have compressible values or keys.
rdbcompression yes
是否采用LZF压缩技术;
# Since version 5 of RDB a CRC64 checksum is placed at the end of the file.
# This makes the format more resistant to corruption but there is a performance
# hit to pay (around 10%) when saving and loading RDB files, so you can disable it
# for maximum performances.
#
# RDB files created with checksum disabled have a checksum of zero that will
# tell the loading code to skip the check.
rdbchecksum yes
RDB在版本5之后在文件末尾加入了CRC64校验和,这使得格式更抗损坏,但是在保存和加载RDB文件时,性能可能会受到影响(大约10%),因此可以禁用它以获得最大性能;
数据库转储文件名
# The filename where to dump the DB
dbfilename dump.rdb
工作目录:
# The working directory.
#
# The DB will be written inside this directory, with the filename specified
# above using the ‘dbfilename‘ configuration directive.
#
# The Append Only File will also be created inside this directory.
#
# Note that you must specify a directory here, not a file name.
dir ./
Redis快照设置:
1.保存到DB的方式;
2.是否采用LZF压缩技术;
3.数据库存储文件名;
4.数据文件存储文件夹;
Tips : 学习一个技术技巧
通用比较函数,支持比较结构体指定字段,支持Linux和Windows
#ifndef _WIN32 #define TYPEOF typeof // linux C98 #else #define TYPEOF decltype // windows C++11后支持 #endif template <int offset, class TYPE> bool CheckZero(const void* p) { TYPE a = *(*TYPE)((char*)p + offset); return (bool)a; } template <int offset, typename T> int CmpOneKey(const void *p1, const void *p2) { T a1 = *(T*)((char*)p1 + offset); T a2 = *(T*)((char*)p2 + offset); if (a1 < a2) return -1; else if (a1 > a2) return 1; return 0; } template <int offset, typename T> int DescCmpOneKey(const void* p1, const void* p2) { return -CmpOneKey<offset, T>(p1, p2); } template <int offset1, typename T1, int offset2, typename T2> int CmpTwoKey(const void* p1, const void* p2) { int diff = CmpOneKey<offset1, T1>(p1, p2); if (diff == 0) { return CmpOneKey<offset2, T2>(p1, p2); } return diff; } template <int offset1, typename T1, int offset2, typename T2> int DescCmpTwoKey(const void *p1, const void *p2) { return -CmpTwoKey<offset1, T1, offset2, T2>(p1, p2); } template <int offset1, typename T1, int offset2, typename T2, int offset3, typename T3> int CmpThreeKey(const void *p1, const void *p2) { int diff = CmpTwoKey<offset1, T1, offset2, T2>(p1, p2); if (diff == 0) { return CmpOneKey<offset3, T3>(p1, p2); } return diff; } #define CHECK_ZERO(s, m) CheckZero<offsetof(s, m), TYPEOF(((s*)0)->m)> #define CMP_ONE_KEY(s, m) CmpOneKey<offsetof(s, m), TYPEOF(((s*)0)->m)> #define CMP_TWO_KEY(s, m1, m2) CmpTwoKey<offsetof(s, m1), TYPEOF(((s*)0)->m1, offsetof(s, m2), TYPEOF(((s*)0)->m2)> #define CMP_THREE_KEY(s, m1, m2, m3) CmpThreeKey()<offsetof(s, m1), TYPEOF(((s*)0)->m1, offsetof(s, m2), TYPEOF(((s*)0)->m2), offsetof(s, m3), TYPEOF(((s*)0)->m3> #define CMP_ONE_KEY_DESC(s, m) DescCmpOneKey<offsetof(s, m), TYPEOF(((s*)0)->m)> #define CMP_TWO_KEY_DESC(s, m1, m2) DescCmpTwoKey<offsetof(s, m1), TYPEOF(((s*)0)->m1, offsetof(s, m2), TYPEOF(((s*)0)->m2)>
Share : 分享一篇有观点和思考的技术文章
TCP三次握手和SYN攻击:
原文链接:https://mp.weixin.qq.com/s?__biz=MzIwNTc4NTEwOQ==&mid=2247484888&idx=1&sn=aaf4f7f4a0b37c8f823e2665d711dd72&scene=21#wechat_redirect
原文地址:https://www.cnblogs.com/yzdai/p/11145456.html