• shell


    1、 Shell overview Shell is a = = command line interpreter = =, which provides users with an interface system level program to send requests to the Linux kernel to run programs. Users can use shell to start, suspend, stop and even write some programs. Shell is also a powerful programming language, easy to write, […]

  • Integer ring


    ring Integer ringZ_mIt consists of the following two parts: 1. AssemblyZ_m = ( 0,1,2,…,m )2. Two kinds of operations “+” and “X” make thea, b\in Z_myes: a + b\equiv c\ mod\ m, (c\in Z_m)\\ a\times b\equiv d\ mod\ m, (d\in Z_m) Key features of rings If the result of the addition or multiplication of any […]

  • Blue Bridge Cup – Max subarray


    For more articles, please pay attention to the official account of “BLOG of the sea”. problem Given a matrix A of nxm, find a nonempty submatrix in a to make the sum of elements in the submatrix maximum.The submatrix of a refers to a block in which the row and column are continuous.Input formatThe first […]

  • Leetcode — add a step on the pit record


    Given aintegerComposed ofNot emptyA nonnegative integer represented by an array.The highest digit is stored in the first place of the array, and each element in the array only storessingleNumbers.You can assume that this integer does not start with zero except for the integer 0. Example 1:Input: [1,2,3]Output: [1,2,4]Explanation:The input array represents the number 123. Example […]

  • Knowledge point — bezu theorem


    On the understanding of bezu theorem In number theory, peishu’s theorem is a theorem aboutGreatest common divisorPeishu theorem is named after French mathematician Etienne peishu. The principle of bezu theorem Peishu theorem (or bezu theorem) is named after French mathematician Etienne peishu,For any [integer] A, B and their greatest common divisor D, the linear Diophantine […]

  • Simplified insertion sort of C language rescue plan day2-1


    //Plan 10 questions every day. Review the questions you have done before //More knocks and more practices will surely make progress! //For the sake of your heart… Go!   This problem requires the preparation of procedures, a given integer inserted into the original orderly integer sequence, so that the result sequence is still orderly. Input […]

  • Rust study notes


    Rust study notes[Variables: VariablesMutable: mutableCompile: compileUnoptimized: not optimizedMismatched: improper collocationScalar: scalarCompound: compound typeParse: a grammatical analysisAnnotation: Annotationtype annotations neededInfer: inferPanic, panicWrapping: wrapping] COMM PROGRAMMING CONCEPTS{variables, basic types, functions, comments, and control flows} KEYWORDSkeywordAppendix AAppendix A Variables and MutabilityVariables and variability Variables in rust are immutable by default. Error: cannot assign twice to immutable variable let […]

  • Algorithm of swift


    Title Description: Given an array of integersnumsAnd a target valuetarget, please find the two integers whose target value is and in the array, and return their array subscript. You can assume that each input corresponds to only one answer. However, the same element in an array cannot be used twice. Example: Given nums = [2, […]

  • Leetcode – Search in 2D array


    Leetcode – Search in 2D array Blog description The information involved in this article comes from Internet collation and personal summary, which means personal learning and experience summary. If there is any infringement, please contact me to delete it. Thank you! explain Jianzhi offer, 4 questions, main station 240 questions Searching in two dimensional array […]

  • Notes on regular expression learning in Python


    purpose Regular expressions can Test patterns within a string replace text Extracting substring from string based on pattern matching Regex syntax Regular expression (regex) uses a single string to match a series of target strings that conform to this syntax rule. A list of metacharacters and their behavior in regex: Metacharacter behavior \ ^ Matches […]

  • The numeric type of MySQL


    The numeric type of MySQL Integer type Integer type containsTINYINT、SMALLINT、MEDIUMINT、INT、 BIGINTEtc. Access range type Storage size Default display width (PCS) Range (signed) Range (no sign) purpose TINYINT(m) 1Byte m:4 -128 – 127 0 – 255 Small integer value SMALLINT(m) 2Byte m:6 -32768 – 32767 0 – 65535 Large integer value MEDIUMINT(m) 3Byte m:9 -8388608 – […]

  • Chapter four: the sum of higher powers and Fermat’s theorem


    a^2 + b^2 = c^2There are many integer solutionsa,b,c。 When exponent 2 is replaced by a larger number, the corresponding equation has a solution.For example, the equation: a_3 + b^3 = c^3,a^4 + b^4 = c^4,a^5 + b^5 = c^2 There are nonzero integer solutionsa,b,cIs that right? The answer is No. Around 1637, Fermat proved […]