Bzoj2243[SDOI2011]染色:树链剖分

题目链接：2243: [SDOI2011]染色

一眼就知道是个树剖……

对于线段树上每个区间，我们维护最左边的颜色、最右边的颜色、总颜色段数

合并区间的时候父区间的颜色段数=左右儿子的颜色段数和-左儿子最右边的颜色是否和有儿子最左边的颜色相等

然而我写炸了一上午QAQ

指针的线段树等于号写成了减号真是看不出来QAQ

令人鸡冻的代码：

#include<cstdio>#include<cstdlib>#include<cstring>#include<iostream>#include<algorithm>using namespace std;const int maxn=1000000+10;struct seg{int l,r,sum;seg *lc,*rc;int cl,cr,data;seg():/*sum(0),*//*cl(-1),cr(-1),*/data(-1){}};seg *root=new seg();int n,m,pos[maxn],ind=0,Belong[maxn];int a[maxn],col[maxn],fa[maxn][21];int dep[maxn],size[maxn],h[maxn],tot=1;struct edge{int to,next;}G[maxn*4];bool vis[maxn];void push_up(seg *p){if (p->l+1==p->r) return;p->cl=p->lc->cl; p->cr=p->rc->cr;p->sum=p->lc->sum+p->rc->sum;if (p->lc!=NULL&&p->rc!=NULL)p->sum-=(p->lc->cr==p->rc->cl);}void push_down(seg *p){if (p->data==-1||p->l+1==p->r) return;p->lc->cl=p->lc->cr=p->data;p->rc->cl=p->rc->cr=p->data;p->lc->data=p->data;p->rc->data=p->data;p->data=-1;p->lc->sum=1;p->rc->sum=1;}void build(seg *p,int l,int r){p->l=l; p->r=r;if (l+1==r){p->cl=p->cr=col[l];p->sum=1; p->lc=NULL;p->rc=NULL; return;}else if (l+1<r){p->lc=new seg();p->rc=new seg();int mid=(l+r)>>1;if (l<mid) build(p->lc,l,mid);else p->lc=NULL;if (mid<r) build(p->rc,mid,r);else p->rc=NULL;push_up(p);}}void add(int x,int y){G[++tot].to=y; G[tot].next=h[x]; h[x]=tot;}void DFS1(int x,int deep){dep[x]=deep; size[x]=1; vis[x]=1;for (int i=1;i<=19;++i){if (dep[x]<(1<<i)) break;fa[x][i]=fa[fa[x][i-1]][i-1];}for (int i=h[x];i;i=G[i].next){int v=G[i].to;if (vis[v]) continue;fa[v][0]=x;DFS1(v,deep+1);size[x]+=size[v];}}void DFS2(int x,int L){int k=0; ++ind; Belong[x]=L;pos[x]=ind; col[ind]=a[x];for (int i=h[x];i;i=G[i].next)   if (dep[x]<dep[G[i].to]&&size[G[i].to]>size[k])      k=G[i].to;if (!k) return; DFS2(k,L);for (int i=h[x];i;i=G[i].next)   if (dep[x]<dep[G[i].to]&&k!=G[i].to)      DFS2(G[i].to,G[i].to);}int query(int a,int b){if (dep[a]<dep[b]) swap(a,b);int t=dep[a]-dep[b];for (int i=0;i<=19;++i)   if (t&(1<<i)) a=fa[a][i];for (int i=19;~i;i--)   if (fa[a][i]!=fa[b][i]){      a=fa[a][i];b=fa[b][i];}if (a==b) return a;else return fa[a][0];}int ask(seg *p,int l,int r){if (l<=p->l&&p->r<=r) return p->sum;if (p->data!=-1) push_down(p);int mid=(p->l+p->r)>>1;if (l<mid&&mid<r){int tmp=p->lc->cr==p->rc->cl?-1:0;tmp+=ask(p->lc,l,r); tmp+=ask(p->rc,l,r); return tmp;}else if (l<mid) {return ask(p->lc,l,r);}else if (mid<r) return ask(p->rc,l,r);}int getcol(seg *p,int po){if (p->l+1==p->r) return p->cl;else {if (p->data!=-1) push_down(p);int mid=(p->l+p->r)>>1;if (po<mid) return getcol(p->lc,po);if (mid<=po) return getcol(p->rc,po);}}int getans(int x,int y){int sum=0;while (Belong[x]!=Belong[y]){sum+=ask(root,pos[Belong[x]],pos[x]+1);int fat=fa[Belong[x]][0];if (getcol(root,pos[Belong[x]])==getcol(root,pos[fat])) sum--;x=fat;} sum+=ask(root,pos[y],pos[x]+1);return sum;}void change(seg *p,int l,int r,int colo){push_down(p);if (l<=p->l&&p->r<=r){p->cl=p->cr=colo;p->sum=1; p->data=colo;return;}else{int mid=(p->l+p->r)>>1;if (l<mid) change(p->lc,l,r,colo);if (mid<r) change(p->rc,l,r,colo);push_up(p);}}void getchange(int x,int y,int z){while (Belong[x]!=Belong[y]){change(root,pos[Belong[x]],pos[x]+1,z);x=fa[Belong[x]][0];}change(root,pos[y],pos[x]+1,z);}int main(){scanf("%d%d",&n,&m);for (int i=1;i<=n;++i) scanf("%d",&a[i]);for (int i=1;i<n;++i){int x,y; scanf("%d%d",&x,&y);add(x,y); add(y,x);}DFS1(1,0); DFS2(1,1);build(root,1,n+1);for (int i=1;i<=m;++i){char s[10]; scanf("%s",s);int x,y,z;if (s[0]=='C'){scanf("%d%d%d",&x,&y,&z);int lca=query(x,y);getchange(x,lca,z);getchange(y,lca,z);}else if (s[0]=='Q'){scanf("%d%d",&x,&y);int lca=query(x,y);int tmp=getans(x,lca);tmp=tmp+getans(y,lca)-1;printf("%d\n",tmp);}}}