Codeforces Round #483 (Div. 1) E. NN country 树上倍增 贪心 欧拉序

#include<cmath>
#include<ctime>
#include<cstdio>
#include<cstring>
#include<cstdlib>
#include<iostream>
#include<algorithm>
#include<iomanip>
#include<vector>
#include<string>
#include<bitset>
#include<queue>
#include<map>
#include<set>
using namespace std;

typedef double db;
typedef long long ll;

inline int read()
{
    int x=0,f=1;char ch=getchar();
    while(ch<'0'||ch>'9'){if(ch=='-')f=-1;ch=getchar();}
    while(ch<='9'&&ch>='0'){x=10*x+ch-'0';ch=getchar();}
    return x*f;
}
void print(int x)
{if(x<0)putchar('-'),x=-x;if(x>=10)print(x/10);putchar(x%10+'0');}

const int N=200100,inf=0X3f3f3f3f;

int last[N],ecnt;
struct EDGE{int to,nt;}e[N];
inline void add(int u,int v)
{e[++ecnt]=(EDGE){v,last[u]};last[u]=ecnt;}

int n;

int dep[N],anc[N][20],low[N][20];

int time_in[N],time_out[N],tim;

// get euler_tour
void dfs(int u)
{
    time_in[u]=++tim;
    for(int i=1;(1<<i)<=dep[u];++i)
        anc[u][i]=anc[anc[u][i-1]][i-1];
    for(int i=last[u];i;i=e[i].nt) dfs(e[i].to);
    time_out[u]=tim;
}

inline int getlca(int u,int v)
{
    if(dep[u]<dep[v]) swap(u,v);
    int len=dep[u]-dep[v];
    for(int i=0;(1<<i)<=len;++i)
        if((1<<i)&len) u=anc[u][i];
    if(u==v) return u;
    for(int i=18;~i;--i)
        if(anc[u][i]!=anc[v][i])
            u=anc[u][i],v=anc[v][i];
    return anc[u][0];
}

inline void update(int &x,int y)
{if(dep[y]<dep[x]) x=y;}

struct node
{
    int x,y,pos;

    friend bool operator <(const node &a,const node &b)
    {return a.x==b.x ? a.pos<b.pos : a.x<b.x;}
}q[N<<3];

int tot;

int bit[N];

inline void modify(int x)
{for(;x<=n;x+=(x&-x)) bit[x]++;}

inline int query(int x)
{
    int res(0);
    for(;x;x-=(x&-x)) res+=bit[x];
    return res;
}

int ans[N],cur[N];
bool book[N];

int main()
{
    n=read();int m,Q;
    register int i,j,u,v,grd;
    for(i=2;i<=n;++i)
        u=anc[i][0]=read(),
        dep[i]=dep[u]+1,add(u,i);
    dfs(1);

    m=read();
    for(i=1;i<=n;++i) low[i][0]=i;
    for(i=1;i<=m;++i)
        u=read(),v=read(),grd=getlca(u,v),
        update(low[u][0],grd),
        update(low[v][0],grd),
        q[++tot]=(node){time_in[u],time_in[v],-inf},
        q[++tot]=(node){time_in[v],time_in[u],-inf};


    for(i=n;i>1;--i) update(low[anc[i][0]][0],low[i][0]);
    for(i=1;i<=18;++i)
        for(u=1;u<=n;++u)
            low[u][i]=low[low[u][i-1]][i-1];
    Q=read();
    for(i=1;i<=Q;++i)
    {
        u=read(),v=read(),grd=getlca(u,v);

        if(dep[low[u][18]]>dep[grd] || dep[low[v][18]]>dep[grd])
        {ans[i]=-1;continue ;}

        for(j=18;~j;--j)
            if(dep[low[u][j]]>dep[grd])
                u=low[u][j],ans[i]+=1<<j;
        for(j=18;~j;--j)
            if(dep[low[v][j]]>dep[grd])
                v=low[v][j],ans[i]+=1<<j;

        if(u==grd || v==grd)
        {ans[i]++;continue ;}
        book[i]=1;
        q[++tot]=(node){time_in[u]-1,time_in[v]-1,i};
        q[++tot]=(node){time_in[u]-1,time_out[v],-i};
        q[++tot]=(node){time_out[u],time_in[v]-1,-i};
        q[++tot]=(node){time_out[u],time_out[v],i};
    }

    sort(q+1,q+1+tot);

    for(i=1;i<=tot;++i)
        if(q[i].pos==-inf) modify(q[i].y);
        else q[i].pos>0 ? cur[q[i].pos]+=query(q[i].y) : cur[-q[i].pos]-=query(q[i].y);

    for(i=1;i<=Q;++i)
    {
        if(cur[i]) ans[i]++;
        else if(book[i]) ans[i]+=2;
        print(ans[i]),puts("");
    }

    return 0;
}