ZOJ 3686 A Simple Tree Problem(线段树)

#include<cstring>
#include<cstdio>
#include<iostream>
#include<cmath>
#include<vector>
#include<algorithm>
#define lc idx<<1
#define rc idx<<1|1
#define lson l,mid,lc
#define rson mid+1,r,rc
#define N 100010

using namespace std;

int n,m;
vector<int>G[N];
int L[N],R[N],id;

struct Tree {
    int st;
    int one;
} tree[N<<2];

void init() {
    for(int i=0; i<=n; i++)
        G[i].clear();
    id=1;
}

void dfs(int fa) {
    L[fa]=id++;
    for(int i=0; i<G[fa].size(); i++) {
        dfs(G[fa][i]);
    }
    R[fa]=id-1;
}

void push_up(int idx) {
    tree[idx].one=tree[lc].one+tree[rc].one;
}

void push_down(int idx,int m) {
    if(tree[idx].st) {
        tree[lc].st^=1,tree[rc].st^=1;
        tree[idx].st=0;
        tree[lc].one=m-m/2-tree[lc].one;
        tree[rc].one=m/2-tree[rc].one;
    }
}

void build(int l,int r,int idx) {
    tree[idx].one=0;
    tree[idx].st=0;
    if(l==r)return;
    int mid=(l+r)>>1;
    build(lson);
    build(rson);
}

void update(int l,int r,int idx,int x,int y) {
    if(x<=l&&r<=y) {
        tree[idx].st^=1;
        tree[idx].one=r-l+1-tree[idx].one;
        return;
    }
    push_down(idx,r-l+1);
    int mid=(l+r)>>1;
    if(x<=mid)update(lson,x,y);
    if(y>mid) update(rson,x,y);
    push_up(idx);
}

int query(int l,int r,int idx,int x,int y) {
    if(x<=l&&r<=y)
        return tree[idx].one;
    push_down(idx,r-l+1);
    int mid=(l+r)>>1;
    int ans=0;
    if(x<=mid) ans+=query(lson,x,y);
    if(y>mid)  ans+=query(rson,x,y);
    return ans;
}

int main() {
    //freopen("test.in","r",stdin);
    while(~scanf("%d%d",&n,&m)) {
        init();
        int fa;
        for(int i=2; i<=n; i++) {
            scanf("%d",&fa);
            G[fa].push_back(i);
        }
        dfs(1);
        build(1,n,1);
        char c[3];
        int rt;
        while(m--) {
            scanf("%s%d",c,&rt);
            if(c[0]=='o') {
                update(1,n,1,L[rt],R[rt]);
                continue;
            }
            printf("%d\n",query(1,n,1,L[rt],R[rt]));
        }
        printf("\n");
    }
    return 0;
}

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