Codeforces 877E - Danil and a Part-time Job（dfs序＋线段树）

877E - Danil and a Part-time Job

思路：dfs序+线段树

dfs序：http://blog.csdn.net/qq_24489717/article/details/50569644

代码：

#include<bits/stdc++.h>
using namespace std;
#define ll long long
#define pb push_back
#define ls rt<<1,l,m
#define rs rt<<1|1,m+1,r
#define mem(a,b) memset(a,b,sizeof(a)) 

const int N=2e5+;
int tree[*N];
int lazy[*N];
int a[N];
int in[N];
int out[N];
vector<int>g[N];
void dfs(int o,int u,int &x)
{
    in[u]=x;
    for(int i=;i<g[u].size();i++)if(g[u][i]!=o)dfs(u,g[u][i],++x);
    out[u]=x;
}
void push_up(int rt)
{
    tree[rt]=tree[rt<<]+tree[rt<<|];
}
void push_down(int rt,int len)
{
    lazy[rt<<]^=lazy[rt];//对lazy数组很巧妙地运用，两次变换相当于没变
    lazy[rt<<|]^=lazy[rt];
    tree[rt<<]=(len-(len>>))-tree[rt<<];
    tree[rt<<|]=(len>>)-tree[rt<<|];
    lazy[rt]=;
}
void build(int rt,int l,int r)
{
    lazy[rt]=;
    if(l==r)
    {
        tree[rt]=a[l];
        return ;
    }
    int m=(l+r)>>;
    build(ls);
    build(rs);
    push_up(rt);
}
void Update(int L,int R,int rt,int l,int r)
{
    if(L<=l&&r<=R)
    {
        lazy[rt]^=;
        tree[rt]=r-l+-tree[rt];
        return ;
    }
    if(lazy[rt])push_down(rt,r-l+);
    int m=(l+r)>>;
    if(L<=m)Update(L,R,ls);
    if(R>m)Update(L,R,rs);
    push_up(rt);
}
int query(int L,int R,int rt,int l,int r)
{
    if(L<=l&&r<=R)return tree[rt];
    if(lazy[rt])push_down(rt,r-l+);
    int m=(l+r)>>;
    int ans=;
    if(L<=m)ans+=query(L,R,ls);
    if(R>m)ans+=query(L,R,rs);
    return ans;
} 

int main()
{
    ios::sync_with_stdio(false);
    cin.tie();
    int n,p,q,t;
    string s;
    cin>>n;
    for(int i=;i<=n;i++)
    {
        cin>>p;
        g[p].pb(i);
        g[i].pb(p);
    }
    int x=;
    dfs(,,x);
    for(int i=;i<=n;i++)cin>>a[in[i]];
    build(,,n);
    cin>>q;
    while(q--)
    {
        cin>>s>>t;
        if(s=="get")cout<<query(in[t],out[t],,,n)<<endl;
        else Update(in[t],out[t],,,n);
    }
    return ;
}