UVA - 12169 -扩展欧几里得算法

#include<iostream>
#include<string.h>
#include<algorithm>
#include<stdio.h>
#define ll long long
#define rep(i,j,k) for(int i=j;i<=k;++i)
using namespace std;
const int maxx = 1e4+7;
ll a[maxx];
void ex_gcd(ll a,ll b,ll &d,ll &x,ll &y)
{
    if (!b)
    {
        d=a;
        x=1;
        y=0;
    }
    else
    {
        ex_gcd(b,a%b,d,y,x);
        y-=x*(a/b);
    }
}
int main()
{
    int n;
    while(~scanf("%d",&n))
    {
        memset(a,0,sizeof(a));
        for (int i=1; i<=2*n; i+=2)
        {
            scanf("%lld",&a[i]);
        }
        ll d,k,b;
        rep(i,0,10000)
        {
            ex_gcd(10001,i+1,d,k,b);
            ll c=(a[3]-(ll)i*i*a[1]);//等式左边
            b=b*c/d;//解数字解
            if(c%d==0)
            {
                int flag;
                rep(j,2,2*n)
                {
                    flag=1;
                    ll tmp=(i*a[j-1]+b)%10001;
                    if (j%2==1)
                    {
                        if (tmp!=a[j])
                        {
                            flag=0;
                            break;
                        }
                    }else {
                       a[j]=tmp;
                    }
                }
                if (flag)
                {
                    break;
                }
            }
            else
            {
                continue;
            }
        }
        for (int i=2;i<=2*n;i+=2){
          printf("%lld\n",a[i]);
        }

    }
    return 0;
}