2014ACM集训13级PK赛3-Modular Inverse

Description

The modular modular multiplicative inverse of an integer a modulo m is an integer x such that a-1≡x (mod m). This is equivalent toax≡1 (mod m).

Input

There are multiple test cases. The first line of input is an integer T ≈ 2000 indicating the number of test cases.

Each test case contains two integers 0 < a ≤ 1000 and 0 < m ≤ 1000.

Output

For each test case, output the smallest positive x. If such x doesn't exist, output "Not Exist".

Sample Input

33 114 125 13

Sample Output

4Not Exist8

 

 

其实怎么也没想到暴力就过了。这简直不科学

#include <stdio.h>#include <math.h>#include <stdlib.h>int main(){    int N;    scanf ("%d",&N);    while (N--)    {        int a,m,x;        int tf = 1;        scanf ("%d%d",&a,&m);        for (x = 1;x <= 100000;x++)            if ((a * x) % m == 1 % m)        {            tf = 0;            break;        }        if (tf)            puts ("Not Exist");        else            printf ("%d\n",x);    }    return 0;}