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Square sum formula N (n+1) (2n+1)/6 i.e. 1^2+2^2+3^2+...+n^2=n (n+1) (2n+

]) Array_chunk () splits an array into multiple arrays, where the number of units per array is determined by size. The number of cells in the last array may be few. The resulting array is a cell in a multidimensional array whose index starts at zero.Setting the optional parameter Preserve_keys to TRUE allows PHP to retain the original key name in the input array. If you specify FALSE, then each result array will be indexed with a new zero-based number. The default value is FALSE.

The script is:nohup/mnt/nand3/h2000g >/dev/null 2>1 For 1 More accurate should be the file descriptor 1, and 1 is generally representative of Stdout_fileno, in fact, this operation is a dup2 (2) call. He standard output to All_re

Example: nohup/mnt/nand3/h2000g >/dev/null 2>1 for 1 More accurate should be the file descriptor 1, and 1 is generally representative of Stdout_fileno, in fact, this operation is a dup2 (2) call. He standard output to All_result,

Tags: Specify output redirection open file and reference Linux also TDE2>1 means that standard error (2) is also directed to the output file of standard output (1).We come to know the following: three standard input and output of Linux, respectively, is Stdin,stdout,stderr, the corresponding number is 0,1,2.STDIN is the standard input, read the information by def

2>1 use A related knowledge 1 By default, the standard input is the keyboard, but it can also come from a file or pipe (pipe |). 2) By default, the standard output is a terminal (terminal), but can also be redirected to a file, pipe or post quotation mark (Backquotes '). 3) By default, standard error output to the

lowercase letters numeric characters $ and _ · Precautions Cannot start with a number Cannot be a keyword in Java Case sensitive Attention: 1: From the name, no more casual, no rules, inadequate surrounding area 2: For precautions, examples show 3: Under those legal, those not valid: helloworld,dataclass,_983, $bS 5_c7,class (x), dataclass# (x), 98.3 (x), Hello World (x) Identifiers (common naming rules) ·

whether a bit is a single bit of 2 groups. */intFindbit1 (intN) {//Find out low start first 1 bit, other clear 0 returnn~ (N-1);//N-n can also}voidFindtwo (intA[],intN) {intANS1 =0, Ans2 =0;intFlag = FindOne (A, n);//All XOR, result =a^b other becomes 0;Flag = FINDBIT1 (flag); for(inti =0; I if(A[i] flag) ans1 ^= a[i];ElseAns2 ^= A[i]; }coutcout//Three. Find

First, the basic idea of inserting sortStarting from the initial ordered subset, the new data elements are constantly inserted into the appropriate position of the ordered sub-set, so that the number of data elements in the child collection is increasing, and when the sub-collection equals the collection, the insertion sort algorithm ends. The commonly used insertion sorting algorithm has two kinds of direct insertion sort and hill sort.　　Second, direct insertion sort1. Definition of direct Inse

0: Indicates keyboard input (stdin)1: Indicates standard output (stdout), system default is 12: Indicates error output (stderr)Command >/dev/null 2>1 = = Command 1>/dev/null 2>1 1) Com

The shell can often be seen: >/dev/null 2>1Eg:sudo kill-9 ' ps-elf |grep-v grep|grep $1|awk ' {print $4} ' 1>/dev/null 2>/dev/nullThe result of the command can be defined in the form of a%> output/dev/null represents an empty device fileWhere does the > delegate redirect to, for example: echo "123" >/home/123.txt1 mean

Use/dev/null 2>1 to do this. This command means that the standard output and error output are all redirected to/dev/null, that is, all the information that is generated is discarded. Here's a look at the difference between command > File 2>file and command > File 2>1 . The f

1. The array sort method is far from being fully exploited and may be more powerful than the developers think. Many developers may feel that the sort method can be used to do this kind of thing: [1, 3, 9, 2].sort (); // return [1, 2, 3, 9] alert ([

in fact to understand the meaning of 2>1, first of all should know that Linux has three kinds of standard input and output, respectively, Stdin,stdout,stderr, the corresponding number is 0,1,2. STDIN is the standard input, the default from the keyboard to read information; stdout is the standard output, the output output to the terminal by default, that is, the monitor and so on; stderr is the standard erro

1. Physics reading (physical read) When the data block is first read, it will be cached in the buffer cache, while the second read and modify the data block in memory buffer cache The following is an example: 1.1 First read: C:\Documents and Settings\paul yi>sqlplus "/as sysdba" Sql*plus:release 9.2.0.4.0-production on Thu Feb 09:32:04 Copyright (c) 1982, 2002, Oracle Corporation. All rights reserved. Connected to:Oracle9i Enterprise Edition Release

1. [Programming Questions] programming questions 1 Time limit: 1 seconds Space limit: 32768K P is a given two-dimensional set of planar integer points. Defines a point x in P, which is called "maximum" if x satisfies any point in P that is not in the upper-right area of x (the horizontal ordinate is greater than X). Find out the collection of all "maximum" points

1, stitching stringThe concatenation string is one of the most commonly used string operations and supports three ways to stitch strings in a PHP tutorial. is a dot. Delimiter {} operation, there is also a dot equals. = to operate, the dot equals sign can decompose a longer string into several lines to define, which is more beneficial. 2, replacement stringIn the language of PHP, a function named Substr_re

In the process of learning Linux, often see some terminal commands or programs have ">/dev/null 2>1" appear, because have met several times, in order to understand clearly, may wish to spend some time Baidu or Google related knowledge.0: Indicates keyboard input (stdin)1: Indicates standard output (stdout), system default is 12: Indicates error output (stderr)Com

Einstein came up with such a mathematical problem: there is a long ladder, if each step across 2, then the last one, if each step across 3, then the last 2 order, if each step across the 5-order, then the last 4 order, if each step across the 6-order, the last remaining 5 order. Only 7 steps at a time, the end is just the first order of no left. How many steps are there in this ladder? Two ways: Method

Crontab-lCrontab-eExecute */5 every five minutes * * * *Executes 0 per hour * * * *Execute 0 */2 per 2 hours * * *Executes 0 0 * * * per dayWeekly Execution 0 0 * 0Monthly execution 0 0 1 * *Annual Execution 0 0 1 1 *Asterisk (*): represents all possible values, such as the