[USACO11DEC]Grass Planting G

树链剖分题目
注意：

1. 要把边权转为点权
2. 计算两条链时，这两条链的公共点被额外算了一次，需要减去它

#include<cstdlib>
#include<cstring>
#include<cstdio>
#include<cctype>
#include<algorithm>
typedef long long LL;
typedef unsigned long long ULL;
namespace FastIo{
    typedef __uint128_t ULLL;
    static char buf[100000],*p1=buf,*p2=buf,fw[100000],*pw=fw;
    #define gc p1==p2&&(p2=(p1=buf)+fread(buf,1,100000,stdin),p1==p2)?EOF:*p1++
    inline void pc(const char &ch){
    	if(pw-fw==100000)fwrite(fw,1,100000,stdout),pw=fw;
    	*pw++=ch;
	}
    #define fsh fwrite(fw,1,pw-fw,stdout),pw=fw
	struct FastMod{
        FastMod(ULL b):b(b),m(ULL((ULLL(1)<<64)/b)){}
        ULL reduce(ULL a){
            ULL q=(ULL)((ULLL(m)*a)>>64);
            ULL r=a-q*b;
            return r>=b?r-b:r;
        }
        ULL b,m;
    }HPOP(10);
    struct QIO{
    	char ch;
    	int st[40];
    	inline char read(){
    		ch=gc;
    		if(ch<'A'||ch>'Z')ch=gc;
    		return ch;
		}
		inline void read(int &x){
    		x=0,ch=gc;
    		while(!isdigit(ch))ch=gc;
    		while(isdigit(ch)){x=(x<<3)+(x<<1)+(ch^48);ch=gc;}
		}
		template<class T>inline void write(T a){
			do{st[++st[0]]=HPOP.reduce(a);a/=10;}while(a);
			while(st[0])pc(st[st[0]--]^48);
			pc('\n');
		}
	}qrw;
}
using namespace FastIo;
#define NUMBER1 200000
#define P(A) A=-~A
#define fione_i(begin,end) for(register int i=begin;i<=end;P(i))
#define ls(rt) rt<<1
#define rs(rt) rt<<1|1
#define mid (l+r>>1)
#define lson l,mid,ls(rt)
#define rson mid+1,r,rs(rt)
#define sz (r-l+1)
#define tt(u) for(register int i=head[u];i;i=e[i].next) 
struct EDGE{int next,to;}e[(NUMBER1<<1)+5];
int depth[NUMBER1+5],size[NUMBER1+5],son[NUMBER1+5],fa[NUMBER1+5],n,head[NUMBER1+5],tot(0),cnt(0),id[NUMBER1+5],top[NUMBER1+5];
struct Segment{
	int tree[(NUMBER1<<2)+5],lazy[(NUMBER1<<2)+5];
	inline void push_up(const int &rt){tree[rt]=tree[ls(rt)]+tree[rs(rt)];}
	inline void change(int l,int r,int rt,int date){tree[rt]+=date*sz,lazy[rt]+=date;}
	inline void push_down(int l,int r,int rt){
		change(lson,lazy[rt]);change(rson,lazy[rt]);
		lazy[rt]=0;
	}
	void intervaland(int l,int r,int rt,int x,int y,int date){
		if(x<=l&&r<=y)return tree[rt]+=sz*date,lazy[rt]+=date,void();
		if(lazy[rt])push_down(l,r,rt);
		if(x<=mid)intervaland(lson,x,y,date);
		if(mid<y)intervaland(rson,x,y,date);
		push_up(rt); 
	}
	int intervalsum(int l,int r,int rt,int x,int y){
		if(x<=l&&r<=y)return tree[rt];
		if(lazy[rt])push_down(l,r,rt);
		int res(0);
		if(x<=mid)res+=intervalsum(lson,x,y);
		if(mid<y)res+=intervalsum(rson,x,y);
		return res;
	}
}seg;
inline void add(const int &u,const int &v){e[++tot].next=head[u];e[tot].to=v,head[u]=tot;}
void dfs1(int u,int fath,int deep){
	depth[u]=deep,fa[u]=fath,size[u]=1;
	int ms(-1); 
	tt(u){
		if(e[i].to==fath)continue;
		dfs1(e[i].to,u,deep+1);
		size[u]+=size[e[i].to];
		if(size[e[i].to]>ms)ms=size[e[i].to],son[u]=e[i].to; 
	}
}
void dfs2(int u,int tf){
	id[u]=++cnt,top[u]=tf;
	if(!son[u])return;
	dfs2(son[u],tf);
	tt(u){
		if(e[i].to==fa[u]||e[i].to==son[u])continue;
		dfs2(e[i].to,e[i].to);
	}
}
inline void treeand(int x,int y){
	while(top[x]!=top[y]){
		if(depth[top[x]]<depth[top[y]])std::swap(x,y);
		seg.intervaland(1,n,1,id[top[x]],id[x],1);
		x=fa[top[x]];
	}
	if(depth[x]>depth[y])std::swap(x,y);
	seg.intervaland(1,n,1,id[x],id[y],1);
	seg.intervaland(1,n,1,id[x],id[x],-1);
}
inline int treesum(int x,int y){
	int ans(0);
	while(top[x]!=top[y]){
		if(depth[top[x]]<depth[top[y]])std::swap(x,y);
		ans+=seg.intervalsum(1,n,1,id[top[x]],id[x]);
		x=fa[top[x]];
	}
	if(depth[x]>depth[y])std::swap(x,y);
	ans+=seg.intervalsum(1,n,1,id[x],id[y]);
	ans-=seg.intervalsum(1,n,1,id[x],id[x]);
	return ans;
}
signed main(){
	int m,x,y;
	char sb;
	qrw.read(n);
	qrw.read(m);
	fione_i(2,n){
		qrw.read(x);
		qrw.read(y);
		add(x,y);add(y,x);
	}
	dfs1(1,0,1);
	dfs2(1,1);
	while(m--){
		sb=qrw.read();
		qrw.read(x);
		qrw.read(y);
		if(sb=='P')treeand(x,y);
		else qrw.write(treesum(x,y));
	}
	fsh;
    exit(0);
    return 0;
}