bfs可以过的，只是我太粗心了，把num写成step了，然后一直错，找了2个多小时，真心好郁闷，害的后来没心情做题目了
[cpp]
/**************************************************************
Problem: 1024
User: yp0408100207
Language: C++
Result: Accepted
Time:670 ms
Memory:1884 kb
****************************************************************/
#include
#include
#include
#include
#include
using namespace std;
int b;
bool flag[100003];
struct N
{
int num,step;
};
int bfs(int a)
{
memset(flag,false,sizeof(flag));
N now,next;
now.num=a;
now.step=0;
queue
q.push(now);
int i;
int temp;
while(!q.empty())
{
now=q.front();
if (now.num==b)
{
return now.step;
}
q.pop();
temp=(int)sqrt((double)now.num);
for (i=1;i<=temp;i++)
if(now.num%i) continue;
int aa=now.num/i;
next.num=now.num+i;
if(next.num<=b&&!flag[next.num])
{
next.step=now.step+1;
flag[next.num]=true;//flag[next.step]=true;哎，弄了好久
q.push(next);
}
if(aa==i) continue;
next.num=now.num+aa;
if(next.num<=b&&!flag[next.num])
{
next.step=now.step+1;
flag[next.num]=true;
q.push(next);
}
}
}
return -1;
}
int main()
{
int a;
while (scanf("%d%d",&a,&b)!=EOF)
{
if(a==b)
{
printf("0\n");
continue;
}
if (a>b)
{
printf("-1\n");
continue;
}
printf("%d\n",bfs(a));
}
return 0;
}