@[_自动AC机_](/space/show?uid=84991) 但不重选的话样例我是读不完的
by Episode9 @ 2018-11-15 22:10:11
@[GREED_VI](/space/show?uid=37409) 你的电脑怎么那么神奇······
by _自动AC机_ @ 2018-11-15 22:11:27
@[GREED_VI](/space/show?uid=37409) Win8？
by _自动AC机_ @ 2018-11-15 22:11:46
@[_自动AC机_](/space/show?uid=84991) win10
by Episode9 @ 2018-11-15 22:12:58
@[_自动AC机_](/space/show?uid=84991) 放评测机也一样
by Episode9 @ 2018-11-15 22:13:13
by Episode9 @ 2018-11-15 22:14:24
@[GREED_VI](/space/show?uid=37409) 那你的电脑是真的神奇了，我也是Win10，不知道为何你的电脑这么秀
by _自动AC机_ @ 2018-11-15 22:17:59
代码搁这了，求救啊啊啊啊
```cpp
#include<bits/stdc++.h>
#define MAXN 1000005
using namespace std;
struct node{int l_son,r_son;};
node tree[MAXN];
int n,val[MAXN],ans=0;
inline int dfs(int l,int r)
{
if ((tree[l].l_son!=-1&&tree[l].r_son!=-1)&&(tree[r].l_son!=-1&&tree[r].r_son!=-1)&&val[tree[l].l_son]==val[tree[r].r_son]&&val[tree[l].r_son]==val[tree[r].l_son])
return dfs(tree[l].l_son,tree[r].r_son)+1+dfs(tree[l].r_son,tree[r].l_son);
if (tree[l].l_son!=-1&&tree[r].r_son!=-1&&tree[l].r_son==-1&&tree[r].l_son==-1&&val[tree[l].l_son]==val[tree[r].r_son])
return dfs(tree[l].l_son,tree[r].r_son)+1;
if (tree[l].r_son!=-1&&tree[r].l_son!=-1&&tree[l].l_son==-1&&tree[r].r_son==-1&&val[tree[l].r_son]==val[tree[r].l_son])
return dfs(tree[l].r_son,tree[r].l_son)+1;
bool flag=1;
if (!(tree[tree[l].l_son].l_son!=-1&&tree[tree[r].r_son].r_son!=-1)) flag=0;
if (!(tree[tree[l].r_son].l_son!=-1&&tree[tree[r].l_son].r_son!=-1)) flag=0;
if (!(tree[tree[l].r_son].r_son!=-1&&tree[tree[r].l_son].l_son!=-1)) flag=0;
if (!(tree[tree[l].r_son].l_son!=-1&&tree[tree[r].l_son].r_son!=-1)) flag=0;
if (flag==0) return -9999999;
}
int main()
{
cin>>n;
for (int i=1;i<=n;i++) cin>>val[i];
for (int i=1;i<=n;i++) cin>>tree[i].l_son>>tree[i].r_son;
for (int i=1;i<=n;i++)
{
int sum=dfs(i,i);
if (sum>ans) ans=sum;
}
cout<<ans*2+1<<endl;
return 0;
}
```
by Episode9 @ 2018-11-15 22:21:20
以上程序不保证正确性，只是想询问输入
by Episode9 @ 2018-11-16 16:00:19
```cpp
#include<bits/stdc++.h>
#define MAXN 1000005
using namespace std;
struct node{int l_son,r_son;};
node tree[MAXN];
int n,val[MAXN],ans=0;
inline int dfs(int l,int r)
{
if (val[l]!=val[r]) return -9999999;
if ((tree[l].l_son!=-1&&tree[l].r_son!=-1)&&(tree[r].l_son!=-1&&tree[r].r_son!=-1))
return dfs(tree[l].l_son,tree[r].r_son)+1+dfs(tree[l].r_son,tree[r].l_son);
if (tree[l].l_son!=-1&&tree[r].r_son!=-1&&tree[l].r_son==-1&&tree[r].l_son==-1)
return dfs(tree[l].l_son,tree[r].r_son)+1;
if (tree[l].r_son!=-1&&tree[r].l_son!=-1&&tree[l].l_son==-1&&tree[r].r_son==-1)
return dfs(tree[l].r_son,tree[r].l_son)+1;
bool flag=1;
if (!((tree[tree[l].l_son].l_son!=-1&&tree[tree[r].r_son].r_son!=-1)||(tree[tree[l].l_son].l_son==-1&&tree[tree[r].r_son].r_son==-1))) flag=0;
if (!((tree[tree[l].r_son].l_son!=-1&&tree[tree[r].l_son].r_son!=-1)||(tree[tree[l].r_son].l_son==-1&&tree[tree[r].l_son].r_son==-1))) flag=0;
if (!((tree[tree[l].r_son].r_son!=-1&&tree[tree[r].l_son].l_son!=-1)||(tree[tree[l].r_son].r_son==-1&&tree[tree[r].l_son].l_son==-1))) flag=0;
if (!((tree[tree[l].r_son].l_son!=-1&&tree[tree[r].l_son].r_son!=-1)||(tree[tree[l].r_son].l_son==-1&&tree[tree[r].l_son].r_son==-1))) flag=0;
if (flag==0) return -9999999;
}
int main()
{
cin>>n;
for (int i=1;i<=n;i++) cin>>val[i];
for (int i=1;i<=n;i++) cin>>tree[i].l_son>>tree[i].r_son;
for (int i=1;i<=n;i++)
{
int sum=dfs(i,i);
if (sum>ans) ans=sum;
}
cout<<ans*2+1<<endl;
return 0;
}
```
这是对的代码，手测
by Episode9 @ 2018-11-16 20:53:34