Mathematics--modulo arithmetic

Wikioi 1200 Congruence equation

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.

Output 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 Sample Input

3 10

Sample output Sample Output

7

Data range and Tips 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

Idea: Seek inverse meta code:

1#include <cstdio>2 #definell Long Long3 4 5 6 voidEXGCD (ll a,ll b,ll &x,ll &y)7 {8     if(b==0)9     {Tenx=1; y=0;return; One     } AEXGCD (b,a%b,x,y); -ll t=x; -x=y; theY=t-(A/b) *y; - } -  -  + intMain () - { +ll A,B;SCANF ("%lld%lld",&a,&b); A ll x, y; at EXGCD (a,b,x,y); -printf"%lld", (x+b)%b); -     return 0; -}

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Mathematics--modulo arithmetic