BJ 集训测试12 同构

http://www.elijahqi.win/archives/2817

#include<cstdio>
#include<vector>
#include<cstring>
#include<algorithm>
#define N 5500
using namespace std;
inline char gc(){
    static char now[1<<16],*S,*T;
    if (T==S){T=(S=now)+fread(now,1,1<<16,stdin);if (T==S) return EOF;}
    return *S++;
}
inline int read(){
    int x=0,f=1;char ch=gc();
    while(ch<'0'||ch>'9') {if (ch=='-') f=-1;ch=gc();}
    while(ch<='9'&&ch>='0') x=x*10+ch-'0',ch=gc();
    return x*f;
}
vector<int> son1[N],son2[N];int num;
int dep1[N],dep2[N];
inline void dfs1(int x){
    int now=num;
    for (int i=0;i<son1[x].size();++i){
        int y=son1[x][i];dep1[++num]=dep1[now]+1;dfs1(y);
    }
}
inline void dfs2(int x){
    int now=num;
    for (int i=0;i<son2[x].size();++i){
        int y=son2[x][i];dep2[++num]=dep2[now]+1;dfs2(y);
    }
}
int dp[2][N];
int main(){
    freopen("t2.in","r",stdin);
    int n1=read();for (int i=2;i<=n1;++i) son1[read()].push_back(i);
    int n2=read();for (int i=2;i<=n2;++i) son2[read()].push_back(i);num=1;
    dep1[1]=1;dfs1(1);dep2[1]=1;num=1;dfs2(1);int pre=0,cur=1;
//  for (int i=1;i<=n1;++i) printf("%d ",dep1[i]);puts("");
//  for (int i=1;i<=n2;++i) printf("%d ",dep2[i]);puts("");
    for (int i=1;i<=n1;++i){
        memset(dp[cur],0,sizeof(dp[cur]));
        for (int j=1;j<=n2;++j){
            dp[cur][j]=max(dp[cur][j-1],dp[pre][j]);
            if (dep1[i]==dep2[j]) dp[cur][j]=max(dp[cur][j],dp[pre][j-1]+1);
        }pre^=1;cur^=1;
    }printf("%d\n",n1+n2-(dp[pre][n2]<<1));
    return 0;
}