1200 同余方程

 1 #include<iostream>
 2 #include<cstdio>
 3 using namespace std;
 4 int x,y;
 5 int gcd(int a,int b,int &x,int &y)
 6 {
 7     if(b==0)
 8     {
 9         x=1;
10         y=0;
11         return a;
12     }
13     int r=gcd(b,a%b,x,y);
14     int tmp=0;
15     tmp=x;
16     x=y;
17     y=(tmp-(a/b)*y);
18     return r;
19     
20 }
21 int main()
22 {
23     int a,b;
24     cin>>a>>b;
25     int r=gcd(a,b,x,y);    
26     while(x<0)
27     {
28         x=b+x;
29     }
30     cout<<x;
31     return 0;
32 }