题目链接(同上一题苹果树)
为什么第10个点T了一晚上。。
下面那个却AC了？跑的也不慢。
TLE:
/*
在DFS序做莫队
当一个点不是另一个点的LCA时，需要加上它们LCA的贡献
*/
#include <cmath>
#include <cstdio>
#include <cctype>
#include <algorithm>
#define gc() getchar()
//#define gc() (SS==TT&&(TT=(SS=IN)+fread(IN,1,MAXIN,stdin),SS==TT)?EOF:*SS++)
const int N=5e4+5,M=1e5+5,MAXIN=2e6;
int n,m,size,Enum,H[N],nxt[N<<1],to[N<<1],dep[N],fa[N],top[N],son[N],sz[N];
int Now,Ans[M],seq[N<<1],in[N],out[N],id,A[N],ref[N],cnt,tm[N];
//char IN[MAXIN],*SS=IN,*TT=IN;
bool vis[N];
struct Ques
{
int l,r,lca,id;
bool operator <(const Ques &a)const{
return l/size<a.l/size?r<a.r:l/size<a.l/size;
}
}q[M];
//inline int read()
//{
// int now=0,f=1;register char c=gc();
// for(;!isdigit(c);c=gc()) if(c=='-') f=-1;
// for(;isdigit(c);now=now*10+c-'0',c=gc());
// return now*f;
//}
inline void AddEdge(int u,int v)
{
to[++Enum]=v, nxt[Enum]=H[u], H[u]=Enum;
to[++Enum]=u, nxt[Enum]=H[v], H[v]=Enum;
}
int Find(int x)
{
int l=1,r=cnt,mid;
while(l<r)
if(ref[mid=l+r>>1]>=x) r=mid;
else l=mid+1;
return l;
}
void Discrete()
{
// for(int i=1; i<=n; ++i) A[i]=ref[i]=read();
for(int i=1; i<=n; ++i) scanf("%d",&A[i]),ref[i]=A[i];
std::sort(ref+1,ref+1+n);
cnt=1;
for(int i=2; i<=n; ++i)
if(ref[i]!=ref[i-1]) ref[++cnt]=ref[i];
for(int i=1; i<=n; ++i) A[i]=Find(A[i]);
}
void Pre_DFS(int x)
{
in[x]=++id, seq[id]=x, sz[x]=1;
int mx=0;
for(int v,i=H[x]; i; i=nxt[i])
if((v=to[i])!=fa[x])
{
fa[v]=x, dep[v]=dep[x]+1, Pre_DFS(v), sz[x]+=sz[v];
if(sz[v]>mx) mx=sz[v],son[x]=v;
}
out[x]=++id, seq[id]=x;
}
void DFS2(int x,int tp)
{
top[x]=tp;
if(son[x])
{
DFS2(son[x],tp);
for(int i=H[x]; i; i=nxt[i])
if(to[i]!=fa[x]&&to[i]!=son[x])
DFS2(to[i],to[i]);
}
}
int Query_LCA(int x,int y)
{
while(top[x]!=top[y])
{
if(dep[top[x]]<dep[top[y]]) std::swap(x,y);
x=fa[top[x]];
}
return dep[x]>dep[y]?y:x;
}
void Calc(int p)
{
if(vis[p])
if(!--tm[A[p]]) --Now;
else ;
else if(++tm[A[p]]==1) ++Now;
vis[p]^=1;
}
int main()
{
// n=read(),m=read();
scanf("%d%d",&n,&m);
Discrete();
// for(int u,v,i=1; i<n; ++i) u=read(),v=read(),AddEdge(u,v);
for(int u,v,i=1; i<n; ++i) scanf("%d%d",&u,&v),AddEdge(u,v);
Pre_DFS(1), DFS2(1,1);
for(int u,v,w,i=1; i<=m; ++i)
{
// u=read(),v=read(),w=Query_LCA(u,v);
scanf("%d%d",&u,&v),w=Query_LCA(u,v);
q[i].id=i;//这要在continue前面。。
if(u==v) {q[i].lca=-1; continue;}
if(in[u]>in[v]) std::swap(u,v);
if(w==u) q[i].l=in[w],q[i].r=in[v],q[i].lca=0;//这部分的LCA不能和u=v时用一样的！
// else if(w==v) q[i].r=in[w],q[i].r=in[u],q[i].lca=0;
else q[i].l=out[u],q[i].r=in[v],q[i].lca=in[w];//in[w] not w!
}
size=sqrt(id), std::sort(q+1,q+1+m);
for(int l=1,r=0,i=1; i<=m; ++i)
if(q[i].lca==-1) Ans[q[i].id]=1;
else
{
while(l<q[i].l) Calc(seq[l++]);
while(l>q[i].l) Calc(seq[--l]);
while(r<q[i].r) Calc(seq[++r]);
while(r>q[i].r) Calc(seq[r--]);
if(q[i].lca) Calc(seq[q[i].lca]);//seq[in[lca]] not in[lca]!
Ans[q[i].id]=Now;
if(q[i].lca) Calc(seq[q[i].lca]);
}
for(int i=1; i<=m; ++i) printf("%d\n",Ans[i]);
return 0;
}AC: 2.21s 8.5M
#include <iostream>
#include <cstdio>
#include <cstring>
#include <algorithm>
#include <cmath>
using namespace std;
typedef long long ll;
const int N = 50010;
struct edge
{
int to, next;
}g[N*2];
int n, m, unit;
struct node
{
int l, r, anc, id;
bool operator <(const node &b)const {return l/unit != b.l/unit ? l/unit < b.l/unit : r < b.r;}
}q[N*2];
int arr[N], ref[N];
int cnt, head[N];
int dep[N];
int in[N], out[N], seq[N*2], num;
int res[N*2], tmp, ver[N];
bool vis[N];
void add_edge(int v, int u)
{
g[cnt].to = u, g[cnt].next = head[v], head[v] = cnt++;
}
void dfs(int v)
{
in[v] = ++num;
seq[num] = v;
for(int i = head[v]; i != -1; i = g[i].next)
{
int u = g[i].to;
if(! dep[u])
dep[u] = dep[v] + 1, dfs(u);
}
out[v] = ++num;
seq[num] = v;
}
namespace Subd
{
int dep[N],fa[N],top[N],son[N],sz[N];
void Pre_DFS(int x)
{
sz[x]=1;
int mx=0;
for(int v,i = head[x]; i != -1; i = g[i].next)
if((v=g[i].to)!=fa[x])
{
fa[v]=x, dep[v]=dep[x]+1, Pre_DFS(v), sz[x]+=sz[v];
if(sz[v]>mx) mx=sz[v],son[x]=v;
}
}
void DFS2(int x,int tp)
{
top[x]=tp;
if(son[x])
{
DFS2(son[x],tp);
for(int v,i = head[x]; i != -1; i = g[i].next)
if((v=g[i].to)!=fa[x]&&v!=son[x])
DFS2(v,v);
}
}
int Query_LCA(int x,int y)
{
while(top[x]!=top[y])
{
if(dep[top[x]]<dep[top[y]]) std::swap(x,y);
x=fa[top[x]];
}
return dep[x]>dep[y]?y:x;
}
}
void Calc(int p)
{
if(vis[p])
if(!--ver[arr[p]]) --tmp;
else ;
else if(++ver[arr[p]]==1) ++tmp;
vis[p]^=1;
}
int tot;
int Find(int x)
{
int l=1,r=tot,mid;
while(l<r)
if(ref[mid=l+r>>1]>=x) r=mid;
else l=mid+1;
return l;
}
void Discrete()
{
for(int i=1; i<=n; ++i) ref[i]=arr[i];
sort(ref+1,ref+1+n);
tot=1;
for(int i=2; i<=n; ++i)
if(ref[i]!=ref[i-1]) ref[++tot]=ref[i];
for(int i=1; i<=n; ++i) arr[i]=Find(arr[i]);
}
//bool cmp(node a, node b){return a.l/unit != b.l/unit ? a.l/unit < b.l/unit : a.r < b.r;}
void solve()
{
int a, b;
for(int i = 1; i <= n; i++)
scanf("%d", &arr[i]);
Discrete();
cnt = 0;
memset(head, -1, sizeof head);
for(int i = 1; i <= n - 1; i++) //存树
scanf("%d%d", &a, &b), add_edge(a, b), add_edge(b, a);
memset(dep, 0, sizeof dep);
dep[1] = 1;
num = 0;
dfs(1);
Subd::Pre_DFS(1), Subd::DFS2(1,1);
for(int u,v,i = 1; i <= m; i++)
{
scanf("%d%d", &u, &v);
q[i].id = i;
if(u == v) q[i].anc = -1; //特殊标记，此时公共祖先应该为1
else
{
int w=Subd::Query_LCA(u,v);
if(in[u]>in[v]) swap(u,v);
if(w==u) q[i].l=in[w],q[i].r=in[v],q[i].anc=0;
else q[i].l=out[u],q[i].r=in[v],q[i].anc=w;
}
}
unit = sqrt(num);
sort(q + 1, q + 1 + m);//分块排序
int l = 1, r = 0;
tmp = 0;
for(int i = 1; i <= m; i++)
if(q[i].anc==-1) res[q[i].id]=1;
else
{
while(l<q[i].l) Calc(seq[l++]);
while(l>q[i].l) Calc(seq[--l]);
while(r<q[i].r) Calc(seq[++r]);
while(r>q[i].r) Calc(seq[r--]);
if(q[i].anc>0) Calc(seq[in[q[i].anc]]);
res[q[i].id]=tmp;
if(q[i].anc>0) Calc(seq[in[q[i].anc]]);
}
for(int i = 1; i <= m; i++) printf("%d\n", res[i]);
}
int main()
{
scanf("%d%d", &n, &m);
solve();
return 0;
}