[Codeforces343D]Water Tree（树链剖分）

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题目描述

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题解

题如其名

代码

#include<algorithm>#include<iostream>#include<cstring>#include<cstdio>#include<cmath>using namespace std;#define N 500005int n,m,dfs_clock;int tot,point[N],nxt[N*2],v[N*2];int size[N],father[N],h[N],son[N],in[N],out[N],top[N];int tr[N*4],delta[N*4]; void add(int x,int y){    ++tot; nxt[tot]=point[x]; point[x]=tot; v[tot]=y;}void dfs_1(int x,int fa){    size[x]=1;father[x]=fa;h[x]=h[fa]+1;    for (int i=point[x];i;i=nxt[i])        if (v[i]!=fa)        {            dfs_1(v[i],x);            size[x]+=size[v[i]];            if (size[v[i]]>size[son[x]]) son[x]=v[i];        }}void dfs_2(int x,int fa){    if (x==son[fa]) top[x]=top[fa];    else top[x]=x;    in[x]=++dfs_clock;    if (son[x]) dfs_2(son[x],x);    for (int i=point[x];i;i=nxt[i])        if (v[i]!=fa&&v[i]!=son[x])            dfs_2(v[i],x);    out[x]=dfs_clock;}void pushdown(int now,int l,int r,int mid){    if (delta[now]!=-1)    {        tr[now<<1]=delta[now<<1]=delta[now];        tr[now<<1|1]=delta[now<<1|1]=delta[now];        delta[now]=-1;    }}void change(int now,int l,int r,int lr,int rr,int opt){    int mid=(l+r)>>1;    if (lr<=l&&r<=rr)    {        tr[now]=opt;        delta[now]=opt;        return;    }    pushdown(now,l,r,mid);    if (lr<=mid) change(now<<1,l,mid,lr,rr,opt);    if (mid+1<=rr) change(now<<1|1,mid+1,r,lr,rr,opt);}int query(int now,int l,int r,int x){    int mid=(l+r)>>1;    if (l==r) return tr[now];    pushdown(now,l,r,mid);    if (x<=mid) return query(now<<1,l,mid,x);    else return query(now<<1|1,mid+1,r,x);}void CHANGE(int u,int t){    int f1=top[u],f2=top[t];    while (f1!=f2)    {        if (h[f1]<h[f2])        {            swap(f1,f2);            swap(u,t);        }        change(1,1,n,in[f1],in[u],0);        u=father[f1];        f1=top[u];    }    if (in[u]>in[t]) swap(u,t);    change(1,1,n,in[u],in[t],0);}int main(){    scanf("%d",&n);    for (int i=1;i<n;++i)    {        int x,y;scanf("%d%d",&x,&y);        add(x,y),add(y,x);    }    dfs_1(1,0);    dfs_2(1,0);    memset(delta,-1,sizeof(delta));    scanf("%d",&m);    for (int i=1;i<=m;++i)    {        int opt,x;scanf("%d%d",&opt,&x);        if (opt==1) change(1,1,n,in[x],out[x],1);        if (opt==2) CHANGE(1,x);        if (opt==3)        {            int ans=query(1,1,n,in[x]);            printf("%d\n",ans);        }    }}

手工栈

#include<algorithm>#include<iostream>#include<cstring>#include<cstdio>#include<cmath>using namespace std;#define N 500005int n,m,dfs_clock;int tot,point[N],nxt[N*2],v[N*2];int size[N],father[N],h[N],son[N],in[N],out[N],top[N];int cur[N],stack[N];bool use[N];int tr[N*4],delta[N*4]; void add(int x,int y){    ++tot; nxt[tot]=point[x]; point[x]=tot; v[tot]=y;}void dfs_1(){    for (int i=1;i<=n;++i) cur[i]=point[i];    size[1]=1,father[1]=0,h[1]=1;    int tmp=0;stack[++tmp]=1;    while (tmp)    {        int x=stack[tmp];        while (cur[x]&&v[cur[x]]==father[x]) cur[x]=nxt[cur[x]];        if (!cur[x])        {            --tmp;            if (father[x])            {                size[father[x]]+=size[x];                if (size[x]>size[son[father[x]]]) son[father[x]]=x;            }            continue;        }        int vt=v[cur[x]];        size[vt]=1,father[vt]=x,h[vt]=h[x]+1;        stack[++tmp]=vt;        cur[x]=nxt[cur[x]];    }}void dfs_2(){    for (int i=1;i<=n;++i) cur[i]=point[i];    in[1]=++dfs_clock,top[1]=1;    int tmp=0;stack[++tmp]=1;    while (tmp)    {        int x=stack[tmp];        if (!use[x])        {            use[x]=1;            if (son[x])            {                int vt=son[x];                in[vt]=++dfs_clock,top[vt]=top[x];                stack[++tmp]=vt;                continue;            }        }        while (cur[x]&&(v[cur[x]]==father[x]||v[cur[x]]==son[x])) cur[x]=nxt[cur[x]];        if (!cur[x])        {            out[x]=dfs_clock;            --tmp;            continue;        }        int vt=v[cur[x]];        in[vt]=++dfs_clock,top[vt]=vt;        stack[++tmp]=vt;        cur[x]=nxt[cur[x]];    }}void pushdown(int now,int l,int r,int mid){    if (delta[now]!=-1)    {        tr[now<<1]=delta[now<<1]=delta[now];        tr[now<<1|1]=delta[now<<1|1]=delta[now];        delta[now]=-1;    }}void change(int now,int l,int r,int lr,int rr,int opt){    int mid=(l+r)>>1;    if (lr<=l&&r<=rr)    {        tr[now]=opt;        delta[now]=opt;        return;    }    pushdown(now,l,r,mid);    if (lr<=mid) change(now<<1,l,mid,lr,rr,opt);    if (mid+1<=rr) change(now<<1|1,mid+1,r,lr,rr,opt);}int query(int now,int l,int r,int x){    int mid=(l+r)>>1;    if (l==r) return tr[now];    pushdown(now,l,r,mid);    if (x<=mid) return query(now<<1,l,mid,x);    else return query(now<<1|1,mid+1,r,x);}void CHANGE(int u,int t){    int f1=top[u],f2=top[t];    while (f1!=f2)    {        if (h[f1]<h[f2])        {            swap(f1,f2);            swap(u,t);        }        change(1,1,n,in[f1],in[u],0);        u=father[f1];        f1=top[u];    }    if (in[u]>in[t]) swap(u,t);    change(1,1,n,in[u],in[t],0);}int main(){    scanf("%d",&n);    for (int i=1;i<n;++i)    {        int x,y;scanf("%d%d",&x,&y);        add(x,y),add(y,x);    }    dfs_1();    dfs_2();    memset(delta,-1,sizeof(delta));    scanf("%d",&m);    for (int i=1;i<=m;++i)    {        int opt,x;scanf("%d%d",&opt,&x);        if (opt==1) change(1,1,n,in[x],out[x],1);        if (opt==2) CHANGE(1,x);        if (opt==3)        {            int ans=query(1,1,n,in[x]);            printf("%d\n",ans);        }    }}

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