洛谷P3128 [USACO15DEC]最大流Max Flow

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链接

　　https://www.luogu.org/problem/show?pid=3128

题解

　　实在找不到LCT模板题了，只好拿这道树剖裸题练手

　　题解：LCT直接做。

代码

//LCT#include <cstdio>#include <algorithm>#define maxn 500000#define inf 0x3f3f3f3fusing namespace std;int N, K;struct node{int w, rev, add;node *f, *ch[2];}nd[maxn], *s[maxn];inline int getwh(node *x){if(!x->f)return -1;if(x->f->ch[0]==x)return 0;if(x->f->ch[1]==x)return 1;return -1;}inline bool isroot(node *x){return getwh(x)==-1;}inline void join(node *x, node *y, int wh){if(x)x->f=y;if(y)y->ch[wh]=x;}inline void rever(node *x){if(x)x->rev^=1;}inline void add(node *x, int v){if(x)x->add+=v;}inline void pushdown(node *x){if(x->add){x->w+=x->add;add(x->ch[0],x->add),add(x->ch[1],x->add);x->add=0;}if(x->rev){swap(x->ch[0],x->ch[1]);rever(x->ch[0]),rever(x->ch[1]);x->rev=0;}}inline void rotate(node *x){node *y=x->f, *z=y->f;int c=getwh(x);if(isroot(y))x->f=y->f;else join(x,z,getwh(y));join(x->ch[!c],y,c);join(y,x,!c);}inline void splay(node *x){node *y;int top=0;for(y=x;!isroot(y);y=y->f)s[++top]=y;s[++top]=y;for(;top;top--)pushdown(s[top]);while(!isroot(x)){y=x->f;if(isroot(y)){rotate(x);break;}if(getwh(x)^getwh(y))rotate(x);else rotate(y);rotate(x);}}inline void access(node *x){node *t=0;while(x){splay(x);x->ch[1]=t;t=x;x=x->f;}}inline void makeroot(node *x){access(x);splay(x);rever(x);}inline void link(node *x, node *y){makeroot(x);x->f=y;}int main(){int i, x, y, ans=-inf;scanf("%d%d",&N,&K);for(i=1;i<N;i++)scanf("%d%d",&x,&y),link(nd+x,nd+y);for(i=1;i<=K;i++){scanf("%d%d",&x,&y);makeroot(nd+x);access(nd+y);splay(nd+y);add(nd+y,1);}for(i=1;i<=N;i++){splay(nd+i);ans=max(ans,nd[i].w);}printf("%d\n",ans);return 0;}

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