我也是第五个点WA，迷之错误，兄弟你bfs不用结构体看着有点难受
```cpp
#include<bits/stdc++.h>
using namespace std;
struct Change{
string a,b;
}a[10];
int len=1;
string s1,s2;
struct NODE{
int step;
string s;
NODE(int a,string x)
{
step=a;
s=x;
}
};
map<string,int> vis;
int ans=-1;
void bfs()
{
queue<NODE> Q;
Q.push(NODE(0,s1));
while (!Q.empty()){
string t=Q.front().s;
int step=Q.front().step;
// cout<<t<<endl;
Q.pop();
if (step>10) break;
if (t==s2){
ans=step;
return;
}
for (int i=1;i<=len;i++){
int pos=t.find(a[i].a);
if (pos==t.npos) continue;
string now;
now=t.substr(0,pos)+a[i].b+t.substr(pos+a[i].a.size(),(t.size()-pos-a[i].a.size()));
// cout<<now<<" "<<step+1<<endl;
if (vis[now]) continue;
vis[now]=1;
Q.push(NODE(step+1,now));
}
}
return;
}
int main()
{
cin>>s1>>s2;
while (cin>>a[len].a>>a[len].b) len++;
len--;
bfs();
if (ans==-1 || ans>10) cout<<"NO ANSWER!\n";
else cout<<ans<<endl;
return 0;
}
```
by 爱新觉罗·弘历 @ 2020-02-04 17:35:51