#树链剖分，线段树#洛谷 1505 [国家集训队]旅游

题目

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分析

边权那就将边权变为深度更大的点的点权，
相反数会影响最值和求和，剩下就是模板了
注意两次相反数的标记要抵消掉

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代码

#include <cstdio>
#include <cctype>
#define rr register
using namespace std;
const int N=200011; struct node{int y,w,next;}e[N<<1];
int top[N],fat[N],wsum[N<<2],wmin[N<<2],wmax[N<<2],lazy[N<<2];
int tot,n,K=1,as[N],dfn[N],dep[N],big[N],son[N],A[N],a[N];
inline signed iut(){
	rr int ans=0,f=1; rr char c=getchar();
	while (!isdigit(c)) f=(c=='-')?-f:f,c=getchar();
	while (isdigit(c)) ans=(ans<<3)+(ans<<1)+(c^48),c=getchar();
	return ans*f;
}
inline void print(int ans){
	if (ans<0) putchar('-'),ans=-ans;
	if (ans>9) print(ans/10);
	putchar(ans%10+48);
}
inline void Swap(int &x,int &y){rr int t=x; x=y; y=t;}
inline signed min(int a,int b){return a<b?a:b;}
inline signed max(int a,int b){return a>b?a:b;}
inline void pup(int k){
    wsum[k]=wsum[k<<1]+wsum[k<<1|1],
	wmin[k]=min(wmin[k<<1],wmin[k<<1|1]),
	wmax[k]=max(wmax[k<<1],wmax[k<<1|1]);
}
inline void ptag(int k){
    Swap(wmin[k],wmax[k]),wsum[k]=-wsum[k],
	wmin[k]=-wmin[k],wmax[k]=-wmax[k],lazy[k]^=1;
}
inline void pdown(int k){ptag(k<<1),ptag(k<<1|1),lazy[k]=0;}
inline void build(int k,int l,int r){
	if (l==r){
		wmin[k]=wmax[k]=wsum[k]=a[l];
		return;
	}
	rr int mid=(l+r)>>1;
	build(k<<1,l,mid);
	build(k<<1|1,mid+1,r);
	pup(k);
}
inline void single(int k,int l,int r,int x,int y){
	if (l==r) {wmin[k]=wmax[k]=wsum[k]=y,lazy[k]=0; return;}
	rr int mid=(l+r)>>1; if (lazy[k]) pdown(k);
	if (x<=mid) single(k<<1,l,mid,x,y);
	    else single(k<<1|1,mid+1,r,x,y);
	pup(k);
}
inline void update(int k,int l,int r,int x,int y){
	if (l==x&&r==y) {ptag(k); return;}
	rr int mid=(l+r)>>1; if (lazy[k]) pdown(k);
	if (y<=mid) update(k<<1,l,mid,x,y);
	else if (x>mid) update(k<<1|1,mid+1,r,x,y);
	else update(k<<1,l,mid,x,mid),update(k<<1|1,mid+1,r,mid+1,y);
	pup(k);
}
inline signed query(int k,int l,int r,int x,int y,int z){
	if (l==x&&r==y){
		if (!z) return wmin[k];
		else if (z==1) return wmax[k];
		    else return wsum[k];
	}
	rr int mid=(l+r)>>1; if (lazy[k]) pdown(k);
	if (y<=mid) return query(k<<1,l,mid,x,y,z);
	else if (x>mid) return query(k<<1|1,mid+1,r,x,y,z);
	else{
		rr int ans1=query(k<<1,l,mid,x,mid,z);
		rr int ans2=query(k<<1|1,mid+1,r,mid+1,y,z);
		if (z==1) return max(ans1,ans2);
		else if (z==2) return ans1+ans2;
		    else return min(ans1,ans2);
	}
}
inline void Update(int x,int y){
	for (;top[x]!=top[y];x=fat[top[x]]){
		if (dep[top[x]]<dep[top[y]]) x^=y,y^=x,x^=y;
		update(1,1,n,dfn[top[x]],dfn[x]);
	}
	if (dep[x]>dep[y]) x^=y,y^=x,x^=y;
	if (dfn[x]<dfn[y]) update(1,1,n,dfn[x]+1,dfn[y]);
}
inline signed Query(int x,int y,int z){
	rr int ans=(z==2)?0:((z==1)?-1001:1001);
	for (;top[x]!=top[y];x=fat[top[x]]){
		if (dep[top[x]]<dep[top[y]]) x^=y,y^=x,x^=y;
		rr int tans=query(1,1,n,dfn[top[x]],dfn[x],z);
		if (z==1) ans=max(ans,tans);
		else if (z==2) ans+=tans;
		    else ans=min(ans,tans);
	}
	if (dep[x]>dep[y]) x^=y,y^=x,x^=y;
	if (dfn[x]<dfn[y]){
	    rr int tans=query(1,1,n,dfn[x]+1,dfn[y],z);
		if (z==1) ans=max(ans,tans);
		else if (z==2) ans+=tans;
		    else ans=min(ans,tans);	    
    }
	return ans;
}
inline void dfs1(int x,int fa){
	dep[x]=dep[fa]+1,fat[x]=fa,son[x]=1;
	for (rr int i=as[x],mson=-1;i;i=e[i].next)
	if (e[i].y!=fa){
		dfs1(e[i].y,x); A[e[i].y]=e[i].w;
		son[x]+=son[e[i].y];
		if (son[e[i].y]>mson) big[x]=e[i].y,mson=son[e[i].y];
	}
}
inline void dfs2(int x,int linp){
	dfn[x]=++tot,top[x]=linp,a[dfn[x]]=A[x];
	if (!big[x]) return; dfs2(big[x],linp);
	for (rr int i=as[x];i;i=e[i].next)
	    if (e[i].y!=fat[x]&&e[i].y!=big[x])
	        dfs2(e[i].y,e[i].y);
}
signed main(){
	n=iut();
	for (rr int i=1;i<n;++i){
		rr int x=iut()+1,y=iut()+1,w=iut();
		e[++K]=(node){y,w,as[x]},as[x]=K;
		e[++K]=(node){x,w,as[y]},as[y]=K;
	}
	dfs1(1,0),dfs2(1,1),build(1,1,n);
	rr char ss[5];
	for (rr int T=iut();T;--T){
		scanf("%s",ss);
		rr int x=iut()+1,y=iut()+1;
        switch (ss[0]){
        	case 'C':{
        		--x; --y;
        		rr int X=e[x<<1].y,Y=e[x<<1|1].y;
        		if (dep[X]<dep[Y]) X^=Y,Y^=X,X^=Y;
        		single(1,1,n,dfn[X],y);
				break;
			}
			case 'N':{
				Update(x,y);
				break;
			}
			case 'S':{
				print(Query(x,y,2)),putchar(10);
				break;
			}
			case 'M':{
				if (ss[1]=='I') print(Query(x,y,0));
				    else print(Query(x,y,1));
				putchar(10);
				break;
			}
		}
	}
	return 0;
}