【BZOJ】2157: 旅游

http://www.lydsy.com/JudgeOnline/problem.php?id=2157

题解：裸lct不解释..

#include <bits/stdc++.h>
using namespace std;
struct node *null;
struct node {
	node *c[2], *f;
	bool flag, rev, tag; int k, sum, mx, mn;
	bool d() { return f->c[1]==this; }
	void setc(node *x, bool d) { c[d]=x; x->f=this; }
	bool check() { return f->c[0]==this || f->c[1]==this; }
	void upd() {
		if(this==null) return;
		tag=!tag; sum=-sum; k=-k;
		swap(mx, mn); mx=-mx; mn=-mn;
	}
	void upd1() {
		if(this==null) return;
		rev=!rev; swap(c[0], c[1]);
	}
	void pushup() {
		sum=c[0]->sum+c[1]->sum+k*flag;
		mx=max(c[0]->mx, c[1]->mx); if(flag) mx=max(mx, k);
		mn=min(c[0]->mn, c[1]->mn); if(flag) mn=min(mn, k);
	}
	void pushdown() {
		if(tag) c[0]->upd(), c[1]->upd(), tag=0;
		if(rev) c[0]->upd1(), c[1]->upd1(), rev=0;
	}
}T[2000005], *it=T;
node *newnode(int k, bool flag) {
	node *x=it++;
	x->c[0]=x->c[1]=x->f=null; x->k=x->sum=k;
	x->tag=x->rev=0; x->flag=flag;
	if(flag) x->mx=x->mn=k;
	else x->mx=-1005, x->mn=1005;
	return x;
}
void rot(node *x) {
	node *f=x->f;
	f->pushdown(); x->pushdown(); bool d=x->d();
	if(f->check()) f->f->setc(x, f->d());
	else x->f=f->f;
	f->setc(x->c[!d], d);
	x->setc(f, !d);
	f->pushup();
}
void fix(node *x) { if(x->check()) fix(x->f); x->pushdown(); }
void splay(node *x) {
	fix(x);
	while(x->check())
		if(!x->f->check()) rot(x);
		else x->d()==x->f->d()?(rot(x->f), rot(x)):(rot(x), rot(x));
	x->pushup();
}
node *access(node *x) {
	node *y=null;
	for(; x!=null; y=x, x=x->f) splay(x), x->c[1]=y;
	return y;
}
void mkroot(node *x) { access(x)->upd1(); splay(x); }
void split(node *x, node *y) { mkroot(x); access(y); splay(y); }
void link(node *x, node *y) { mkroot(x); x->f=y; }

void init() {
	null=it++;
	null->c[0]=null->c[1]=null->f=null;
	null->k=null->sum=0;
	null->rev=null->flag=null->tag=0;
	null->mx=-1005; null->mn=1005;
}

void change(node *x, int k) {
	splay(x);
	x->k=k;
	x->pushup();
}
void update(node *x, node *y) {
	split(x, y);
	y->upd();
}
void getsum(node *x, node *y) {
	split(x, y); printf("%d\n", y->sum);
}
void getmx(node *x, node *y) {
	split(x, y); printf("%d\n", y->mx);
}
void getmn(node *x, node *y) {
	split(x, y); printf("%d\n", y->mn);
}
node *nd[200005], *ed[200005];
int main() {
	init();
	int n, q;
	scanf("%d", &n);
	for(int i=0; i<n; ++i) nd[i]=newnode(0, 0);
	for(int i=1; i<n; ++i) {
		int x, y, k; scanf("%d%d%d", &x, &y, &k);
		ed[i]=newnode(k, 1);
		link(nd[x], ed[i]); link(ed[i], nd[y]);
	}
	scanf("%d", &q); char s[5];
	while(q--) {
		int x, y;
		scanf("%s%d%d", s, &x, &y);
		if(s[0]=='C') change(ed[x], y);
		else if(s[0]=='N') update(nd[x], nd[y]);
		else if(s[0]=='S') getsum(nd[x], nd[y]);
		else {
			if(s[1]=='A') getmx(nd[x], nd[y]);
			else getmn(nd[x], nd[y]);
		}
	}
	return 0;
}

　　

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lct倒是半小时1次码好无错误 = =可是坑爹的题 ：编号从0～n-1。。。坑了我好久啊= =

当练手速= =