## C + + singleton mode and thread safety

C + + singleton mode and thread safety The simplest singleton mode can be // single thread safe version class Singleton { public: static Singleton* GetInstance(int x = 0) { if (instance_ == NULL) { instance_ = new Singleton(x); } return instance_; } void Print() { ...

Added by sheen.andola on Sat, 05 Mar 2022 11:48:04 +0200

## Explanation of Gauss elimination method

The essence of Gauss elimination is to simplify it into a stepped determinant. Firstly, the solutions of linear equations are as follows: unsolvableThere are infinite solutionsUnique solution The steps of Gaussian elimination are divided into the following four steps: Enumerate each row to find the maximum absolute value of the current colu ...

Added by slashpine on Tue, 08 Feb 2022 03:29:04 +0200

## Segment tree -- interval maximum gcd problem

AcWing 246. Interval maximum common divisor Given A sequence A with length N and M instructions, each instruction may be one of the following two: C l r d means adding d to A[l],A[l+1],..., A[r]. Q l r, represents the maximum common divisor (GCD) of query A[l],A[l+1],..., A[r]. For each query, an integer is output to represent the answer. Inp ...

Added by brad_fears on Tue, 25 Jan 2022 04:50:31 +0200

## Codeforces 1547f array stabilization (GCD version)

Title Link: Array Stabilization (GCD version) General meaning Given an array of length n, the subscripts are from 1 to n. where an and a1 are connected (form a ring) Each round of operation yields a new array b: for all I ∈ [1, n], b[i] = gcd(a[i], a[i + 1]) (b[n] = gcd(a[n], a[1]) Finally, copy the new array b to the original array a ...

Added by john-iom on Wed, 19 Jan 2022 11:52:20 +0200

## Modular combination - Lucas/exLucas - LibreOJ #181 Binomial coefficient

Proof and code are separated, and you can jump according to your own needs. Go to my Blog, maybe the reading effect is better Lucas theorem ( n ...

Added by js_280 on Fri, 14 Jan 2022 16:09:37 +0200

## Number theory: application of maximum common divisor and minimum common multiple: Hankson's interesting problem

Summary: 1. If LCM (b, x) = = d, (the least common multiple of b, x = = d), you should know that B and X are divisors of d. 2. When b and x are divisors of d, the prime factors in b and x exist in the least common multiple of d. 3. Number of divisors: the upper bound of the number of divisors of n is sqrt(n), that is, there are at ...

Added by kid_c on Mon, 10 Jan 2022 21:09:41 +0200

## Special test mathematics 3

A. Solving equation It is easy to do without considering the two restrictions. Use the board inserting method to divide \ (m \) balls into \ (n \) piles It's \ (\ binom{m-1}{n-1} \) The second limit is greater than or equal to, so you can allocate \ (a_i-1 \) to these numbers first The first restriction is not easy to do directly, so consider i ...

Added by froggie81 on Fri, 07 Jan 2022 13:28:39 +0200

## [record] math #1

10000 euro / Class Euro Euclidean like algorithm Board board. [template] Euclidean algorithm #include<bits/stdc++.h> #define ll long long #define N 22 #define P 998244353 ll t,p,q,r,l; struct Po{ ll cntu,cntr,sumi,sums,sqrs,prod; Po(){cntu = cntr = sumi = sums = sqrs = prod = 0;} Po operator + (Po b) { Po c; c.cntu=(cntu+b.cntu ...

Added by crimaniak on Thu, 30 Dec 2021 15:46:44 +0200

## Extended Euclidean and bezu theorem

summary Extended Euclid is used to solve the relevant equations a x + b y = m ax+by=m The problem of ax+by=m European ex ...

Added by benwilhelm on Fri, 22 Oct 2021 10:50:16 +0300