[NOIP2012 Improvement Group] Codevs 1200 with congruence (extended Euclidean algorithm)

Number of topics: All number theory is disgusting to me. Don't want to say anything more.

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#include <iostream> using namespace std; void gcd (int a,int b,int &x,int &y) {if (!b) {x=1; y=0;}else {GCD (B,a%b,x,y);int t=x; X=y;Y=t-a/b*x;}} int main () {//Freopen ("Test.in", "R", stdin);//Freopen ("Test.out", "w", stdout);int a,b,x,y;cin>>a>>b;GCD (A,b,x,y);cout<< (x%b+b)%b<<endl; return 0;}

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1200 congruence equation

2012 Noip National League Improvement Group

time limit: 1 s space limit: 128000 KB   Title level: Diamonds Diamond Solving

Title Description Description

The minimum positive integer solution for ax≡1 (mod b) of the x congruence equation is obtained.

Enter a description input Description

Enter only one row, containing two positive integers a, b, separated by a space.

outputs description output Description

The output has only one row containing a positive integer x0, or a minimum positive integer solution, and the input data guarantees there must be a solution.

sample input to sample

3 10

Sample output Sample outputs

7

data size & Hint

"Data Range"
For 40% of data, 2≤b≤1,000;
For 60% of data, 2≤b≤50,000,000
For 100% of data, 2≤a, b≤2,000,000,000

[NOIP2012 Improvement Group] Codevs 1200 with congruence (extended Euclidean algorithm)