CF620E New Year Tree（dfs序+线段树）

[link](https://codeforces.com/contest/620/problem/E)

// Problem: CF620E New Year Tree
// Contest: Luogu
// URL: https://www.luogu.com.cn/problem/CF620E
// Memory Limit: 250 MB
// Time Limit: 3000 ms
// 
// Powered by CP Editor (https://cpeditor.org)

#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef unsigned long long ull;
typedef pair<ll, ll>PLL;
typedef pair<int, int>PII;
typedef pair<double, double>PDD;
#define I_int ll
inline ll read()
{
    ll x = 0, f = 1;
    char ch = getchar();
    while(ch < '0' || ch > '9')
    {
        if(ch == '-')f = -1;
        ch = getchar();
    }
    while(ch >= '0' && ch <= '9')
    {
        x = x * 10 + ch - '0';
        ch = getchar();
    }
    return x * f;
}

inline void out_(ll x){
    if (x < 0) x = ~x + 1, putchar('-');
    if (x > 9) out_(x / 10);
    putchar(x % 10 + '0');
}

inline void write(ll x){
    if (x < 0) x = ~x + 1, putchar('-');
    if (x > 9) write(x / 10);
    putchar(x % 10 + '0');
    puts("");
}

#define read read()
#define closeSync ios::sync_with_stdio(0);cin.tie(0);cout.tie(0)
#define multiCase int T;cin>>T;for(int t=1;t<=T;t++)
#define rep(i,a,b) for(int i=(a);i<=(b);i++)
#define repp(i,a,b) for(int i=(a);i<(b);i++)
#define per(i,a,b) for(int i=(a);i>=(b);i--)
#define perr(i,a,b) for(int i=(a);i>(b);i--)
ll ksm(ll a, ll b, ll p)
{
    ll res = 1;
    while(b)
    {
        if(b & 1)res = res * a % p;
        a = a * a % p;
        b >>= 1;
    }
    return res;
}
const int inf = 0x3f3f3f3f;
#define PI acos(-1)
const int maxn=4e5+100;

int n,m;
ll c[maxn];
int e[maxn*2],ne[maxn*2],h[maxn],idx;
int in[maxn],out[maxn],tot,pos[maxn];
struct node{
    int l,r;
    ll laz,sum;
}tr[maxn*4];

ll lowbit(ll x){
    return x&(-x);
}

void add(int u,int v){
    e[++idx]=v,ne[idx]=h[u],h[u]=idx;
}
void dfs(int u,int fa){
    in[u]=++tot;
    pos[tot]=u;
    /*for(int i=0;i<g[u].size();i++){
        int j=g[u][i];
        if(j==fa) continue;
        dfs(j,u);
    }*/
    for(int i=h[u];i+1;i=ne[i]){
        int j=e[i];
        if(j==fa) continue;
        dfs(j,u);
    }
    out[u]=tot;
}

void pushup(int u){
    tr[u].sum=tr[u<<1].sum|tr[u<<1|1].sum;
    return ;
}

void pushdown(int u){
    if(tr[u].laz!=0){
        tr[u<<1].laz=tr[u<<1|1].laz=tr[u].laz;
        tr[u<<1].sum=tr[u<<1|1].sum=(tr[u].laz);
        tr[u].laz=0;
    }
}

void build(int u,int l,int r){
    tr[u].l=l,tr[u].r=r;
    if(l==r){
        tr[u].laz=0;
        tr[u].sum=(1ll<<c[pos[l]]);
        return ;
    }
    int mid=(l+r)/2;
    build(u<<1,l,mid);
    build(u<<1|1,mid+1,r);
    pushup(u);
}

void update(int u,int l,int r,ll v){
    //if(tr[u].l>r||tr[u].r<l) return ;
    if(tr[u].l>=l&&tr[u].r<=r){
        tr[u].sum=(ll)(1ll<<v);
        tr[u].laz=(ll)(1ll<<v);
        return ;
    }
    pushdown(u);
    int mid=(tr[u].l+tr[u].r)/2;
    if(l<=mid) update(u<<1,l,r,v);
    if(r>mid) update(u<<1|1,l,r,v);
    pushup(u);
}

ll qask(int u,int l,int r){
    //if(tr[u].l>r||tr[u].r<l) return 0;
    if(tr[u].l>=l&&tr[u].r<=r){
        return tr[u].sum;
    }
    pushdown(u);
    ll res=0;
    int mid=(tr[u].l+tr[u].r)/2;
    if(l<=mid) res|= qask(u<<1,l,r);
    if(r>mid) res|=qask(u<<1|1,l,r);
    pushup(u);
    return res;
}


int main(){
    memset(h,-1,sizeof h);
    n=read,m=read;
    rep(i,1,n) c[i]=read;
    rep(i,1,n-1){
        int u=read,v=read;
        add(u,v);add(v,u);
    }
    dfs(1,0);
    build(1,1,n);
    /*rep(i,1,n){
        cout<<in[i]<<"++++++++"<<out[i]<<"
";
    }*/
    while(m--){
        int op=read;
        if(op==1){
            int u=read;
            ll v=read;
            update(1,in[u],out[u],v);
        }
        else{
            int u=read;
            ll res=qask(1,in[u],out[u]);
            //cout<<res<<"-******"<<endl;
            ll ans=0;
            while(res){
                ans++;
                res-=lowbit(res);
            }
            printf("%lld
",ans);
        }
    }
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    return 0;
}