Logu P2486 [sdoi2011] coloring (tree chain + segment tree + merging of intervals on the tree)

Luogu P2486 [SDOI2011] dyeing （ Tree chain + Line segment tree + Interval merging on tree ）

The question ：

Given a tree n Rootless tree with nodes , share m Operations , There are two kinds of operations ：

The nodes a To the node b All points on the path of （ Include a and b） All dyed in color c.

Ask nodes a To the node b Number of color segments on the path of .

A color segment is defined as an extremely long continuous segment of the same color . for example 112221 It consists of three sections ：11、222、1

Ideas ：

When merging intervals on a tree , Consider the last boundary

#include <bits/stdc++.h>
using namespace std;
#define lson rt<<1,l,mid
#define rson rt<<1|1,mid+1,r
typedef long long ll;
const int INF=0x3f3f3f3f;
const int maxn=2e5+100;
int n,m,k,RC,LC,tot,a[maxn],siz[maxn],fa[maxn],son[maxn],id[maxn],idd[maxn],top[maxn],deep[maxn],lazy[maxn<<2];
vector<int>mp[maxn];
struct NODE{
    
	ll ans,sum,ml,mr,l,r;
}tree[maxn<<2];
void dfs1(int x,int f,int d){
    
	siz[x]=1;
	fa[x]=f;
	deep[x]=d;
	son[x]=0;
	for(auto y:mp[x]){
    
		if(y==f)continue;
		dfs1(y,x,d+1);
		siz[x]+=siz[y];
		if(siz[son[x]]<siz[y])son[x]=y;
	}
}
void dfs2(int x,int root){
    
	id[x]=++tot;
	top[x]=root;
	idd[tot]=a[x];
	if(son[x])dfs2(son[x],root);
	for(auto y:mp[x]){
    
		if(y!=fa[x]&&y!=son[x])dfs2(y,y);
	}
}
void pushup(int rt){
    
	tree[rt].sum=tree[rt<<1].sum+tree[rt<<1|1].sum;
	if(tree[rt<<1].mr==tree[rt<<1|1].ml)tree[rt].sum--;
	tree[rt].ml=tree[rt<<1].ml,tree[rt].mr=tree[rt<<1|1].mr;
}
void pushdown(int rt){
    
	if(lazy[rt]){
    
		tree[rt<<1].ml=tree[rt<<1|1].mr=lazy[rt];
		tree[rt<<1].mr=tree[rt<<1|1].ml=lazy[rt];
		tree[rt<<1].sum=tree[rt<<1|1].sum=1;
		lazy[rt<<1]=lazy[rt<<1|1]=lazy[rt];
		lazy[rt]=0;
	}
}
void build(int rt,int l,int r){
    
	tree[rt].l=l,tree[rt].r=r;
	if(l==r){
    
		tree[rt].ml=tree[rt].mr=idd[l];
		tree[rt].sum=1;
		return;
	}
	int mid=(l+r)>>1;
	build(rt<<1,l,mid);
	build(rt<<1|1,mid+1,r);
	pushup(rt);
}
void update(int rt,int x,int y,int c){
    
	if(x<=tree[rt].l&&tree[rt].r<=y){
    
		tree[rt].ml=tree[rt].mr=c;
		tree[rt].sum=1;
		lazy[rt]=c;
		return;
	}
	pushdown(rt);
	int mid=(tree[rt].l+tree[rt].r)>>1;
	if(x<=mid)update(rt<<1,x,y,c);
	if(y>mid)update(rt<<1|1,x,y,c);
	pushup(rt);
}
NODE query(int rt,int x,int y,int xx,int yy){
    
	if(x<=tree[rt].l&&tree[rt].r<=y){
    
		if(tree[rt].l==xx)LC=tree[rt].ml;
		if(tree[rt].r==yy)RC=tree[rt].mr;
		return tree[rt];
	}
	int mid=(tree[rt].l+tree[rt].r)>>1;
	pushdown(rt);
	if(y<=mid)return query(rt<<1,x,y,xx,yy);
	else if(x>mid)return query(rt<<1|1,x,y,xx,yy);
	else{
    
		NODE t,t1=query(rt<<1,x,mid,xx,yy),t2=query(rt<<1|1,mid+1,y,xx,yy);
		t.ml=t1.ml;
		t.mr=t2.mr;
		t.sum=t1.sum+t2.sum;
		if(t1.mr==t2.ml)t.sum--;
		return t;
	}
}
int getdis(int x,int y){
    // The poem  
	int ans=0,pos1=0,pos2=0;//pos1 by x, Upper endpoint color of points with large depth  
	while(top[x]!=top[y]){
    
		if(deep[top[x]]<deep[top[y]])swap(x,y),swap(pos1,pos2);
		ans+=query(1,id[top[x]],id[x],id[top[x]],id[x]).sum;
		if(RC==pos1)ans--;
		pos1=LC;
		x=fa[top[x]];
	}
	if(deep[x]>deep[y])swap(x,y),swap(pos1,pos2);
	ans+=query(1,id[x],id[y],id[x],id[y]).sum;
	if(LC==pos1)ans--;
	if(RC==pos2)ans--;
	return ans;
}
void upday(int x,int y,int c){
    //x To y Interval modification  
	while(top[x]!=top[y]){
    
		if(deep[top[x]]<deep[top[y]])swap(x,y);
		update(1,id[top[x]],id[x],c);
		x=fa[top[x]];
	}
	if(deep[x]>deep[y])swap(x,y);
	update(1,id[x],id[y],c);
}
int main(){
    
	scanf("%d%d",&n,&m);
	for(int i=1;i<=n;i++){
    
		scanf("%d",&a[i]);
	}
	for(int i=1,x,y;i<n;i++){
    
		scanf("%d%d",&x,&y);
		mp[x].push_back(y),mp[y].push_back(x);
	}
	dfs1(1,0,1);
	dfs2(1,1);
	build(1,1,n);
	for(int i=1,x,y,z;i<=m;i++){
    
		char op[10];
		scanf("%s%d%d",op,&x,&y);
		if(op[0]=='Q')printf("%d\n",getdis(x,y));
		else{
    
			scanf("%d",&z);
			upday(x,y,z);
		}
	}
}