UVA 10277 Boastin' Red Socks

#include <iostream>
#include<cstdio>
#include<cstring>

using namespace std;

unsigned int r,sum,p,q;
unsigned int st[50010][2];

unsigned gcd(unsigned a,unsigned b)
{
    return b?gcd(b,a%b):a;
}
/*哈希链表*/
const int HASH=50007;
int head[HASH],next1[HASH];
int hash1(unsigned int &s)
{
    return s%HASH;
}
int insert(int s)
{
    int h=hash1(st[s][0]);
    int u=head[h];
    while(u)//链表尾一直是0，所以s不能为0
        u=next1[u];
    next1[s]=head[h];//原来的链表头成为s的next
    head[h]=s;//s成为head[h]的链表头
    return 1;
}
int find(unsigned int s)
{
    int h=hash1(s);
    int u=head[h];
    while(u)
    {
        if(st[u][0]==s) return u;
        u=next1[u];
    }
    return 0;
}
int main()
{
    //freopen("/home/user/桌面/in","r",stdin);
    while(scanf("%u%u",&p,&q)==2&&(p||q))
    {
        memset(head,0,sizeof(head));
        unsigned int i=2,x,j=1;
        if(p==0)
        {
            printf("%d %d
",0,2);
            continue;
        }
        x=gcd(p,q);
        p/=x;q/=x;
        for(;i<=50000;i++)
        {
            unsigned int t=i*i-i;
            if(t%p==0)
            {
                st[j][0]=t/p;
                st[j][1]=i;
                insert(j);
                j++;
            }
            if(t%q==0&&(x=find(t/q)))
            {
                printf("%u %u
",st[x][1],i-st[x][1]);
                break;
            }
        }
        if(i>50000) puts("impossible");
    }
    return 0;
}