部落冲突

传送门

树剖板子题……开战的话我们把深度比较深的那个点点权设为1，然后每次在一条路径上query即可。停战的话改回来。

#include<cstdio>
#include<algorithm>
#include<cstring>
#include<iostream>
#include<cmath>
#include<set>
#include<queue>
#define rep(i,a,n) for(int i = a;i <= n;i++)
#define per(i,n,a) for(int i = n;i >= a;i--)
#define enter putchar('
')

using namespace std;
typedef long long ll;
const int M = 300005;
const int INF = 1000000009;

int read()
{
    int ans = 0,op = 1;
    char ch = getchar();
    while(ch < '0' || ch > '9')
    {
    if(ch == '-') op = -1;
    ch = getchar();
    }
    while(ch >= '0' && ch <= '9')
    {
    ans *= 10;
    ans += ch - '0';
    ch = getchar();
    }
    return ans * op;
}

struct edge
{
    int next,to;
}e[M<<1];

struct seg
{
    int v;
}t[M<<2];

int n,m,p,q,dep[M],size[M],top[M],hson[M],head[M],dfn[M],war[M],ecnt,x,idx,cnt,fa[M];
char s[5];

void add(int x,int y)
{
    e[++ecnt].to = y;
    e[ecnt].next = head[x];
    head[x] = ecnt;
}

int Max(int x,int y)
{
    return (dep[x] > dep[y]) ? x : y;
}

void dfs1(int x,int f,int depth)
{
    size[x] = 1,fa[x] = f,dep[x] = depth;
    int maxson = -1;
    for(int i = head[x];i;i = e[i].next)
    {
    if(e[i].to == f) continue;
    dfs1(e[i].to,x,depth+1);
    size[x] += size[e[i].to];
    if(size[e[i].to] > maxson) maxson = size[e[i].to],hson[x] = e[i].to;
    }
}

void dfs2(int x,int t)
{
    top[x] = t,dfn[x] = ++idx;
    if(!hson[x]) return;
    dfs2(hson[x],t);
    for(int i = head[x];i;i = e[i].next)
    {
    if(e[i].to == fa[x] || e[i].to == hson[x]) continue;
    dfs2(e[i].to,e[i].to);
    }
}

void modify(int p,int l,int r,int pos,int val)
{
    if(l == r)
    {
    t[p].v = val;
    return;
    }
    int mid = (l+r) >> 1;
    if(pos <= mid) modify(p<<1,l,mid,pos,val);
    else modify(p<<1|1,mid+1,r,pos,val);
    t[p].v = t[p<<1].v + t[p<<1|1].v;
}

int query(int p,int l,int r,int kl,int kr)
{
    if(l == kl && r == kr) return t[p].v;
    int mid = (l+r) >> 1;
    if(kr <= mid) return query(p<<1,l,mid,kl,kr);
    else if(kl > mid) return query(p<<1|1,mid+1,r,kl,kr);
    else return query(p<<1,l,mid,kl,mid) + query(p<<1|1,mid+1,r,mid+1,kr);
}

void mrange(int x,int y)
{
    while(top[x] != top[y])
    {
    if(dep[top[x]] < dep[top[y]]) swap(x,y);
    int g = query(1,1,n,dfn[top[x]],dfn[x]);
    if(g)
    {
        printf("No
");
        return;
    }
    x = fa[top[x]];
    }
    if(dep[x] > dep[y]) swap(x,y);
    if(dfn[x] + 1 > dfn[y])
    {
    printf("Yes
");
    return;
    }
    int g = query(1,1,n,dfn[x]+1,dfn[y]);
    g ? printf("No
") : printf("Yes
");
}

int main()
{
    n = read(),m = read();
    rep(i,1,n-1) p = read(),q = read(),add(p,q),add(q,p);
    dfs1(1,1,0),dfs2(1,1);
    rep(i,1,m)
    {
    scanf("%s",s);
    if(s[0] == 'Q') p = read(),q = read(),mrange(p,q);
    else if(s[0] == 'C') p = read(),q = read(),modify(1,1,n,dfn[Max(p,q)],1),war[++cnt] = Max(p,q);
    else if(s[0] == 'U') x = read(),modify(1,1,n,dfn[war[x]],0);
    }
    return 0;
}