zoj 3609 Modular Inverse

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

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Output

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

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Sample Input

33 114 125 13

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Sample Output

4Not Exist8

References

• http://en.wikipedia.org/wiki/Modular_inverse

#include<stdio.h>#include<string.h>#include<cmath>#include<algorithm>using namespace std;int main(){    int t,a,mod;    scanf("%d",&t);    while(t--)    {        scanf("%d%d",&a,&mod);        int flag = 1;        for(int i = 1; i <= 1000; i++)        {            if((1-a*i)%mod == 0)            {                flag = 0;                printf("%d\n",i);                break;            }        }        if(flag)printf("Not Exist\n");    }}