hdu 1104 数论+bfs

#include<iostream>
#include<queue>
using namespace std;
struct Node
{
int x;
int step;
queue<char> q;
};
int v[1000010];
int n,m,k;
bool bfs()
{
int s=((n+1)%k+k)%k;
queue<Node>q;
Node now,next;
now.x=n;now.step=0;
q.push(now);
memset(v,0,sizeof(v));
while(!q.empty())
{
now=q.front();
if((now.x%k+k)%k==s)
{
printf("%d\n",now.step);
while(now.step--)
{
printf("%c",now.q.front());
now.q.pop();
}
printf("\n");
return true;
}
q.pop();
int xx;
xx=(now.x+m)%(k*m);
if(!v[(xx%k+k)%k])
{
v[(xx%k+k)%k]=1;
next=now;next.x=xx;next.q.push('+');next.step++;
q.push(next);
}
xx=(now.x-m)%(k*m);
if(!v[(xx%k+k)%k])
{
v[(xx%k+k)%k]=1;
next=now;next.x=xx;next.q.push('-');next.step++;
q.push(next);
}
xx=(now.x*m)%(k*m);//因为xx会变得很大 所以要求余变小
if(!v[(xx%k+k)%k])
{
v[(xx%k+k)%k]=1;
next=now;next.x=xx;next.q.push('*');next.step++;
q.push(next);
}
xx=((now.x%m+m)%m)%(m*k);
if(!v[(xx%k+k)%k])
{v[(xx%k+k)%k]=1;
next=now;next.x=xx;next.q.push('%');next.step++;
q.push(next);
}
}
return 0;
}
int main()
{

while(scanf("%d%d%d",&n,&k,&m)!=EOF)
{
if(n==0&&k==0&&m==0)
break;
if(!bfs())
printf("0\n");
}
return 0;
}