2016年3月6日 星期日

[SPOJ COT3]COT3 - Combat on a tree (優化後的code)

請先參考這裡的題解

優化1:
$trie$的新節點從動態宣告改成靜態宣告 ($replacement\ new$)

優化2:
$trie$單字結尾的訊息使用鏈表來儲存,做到$O(1)$合併
原本是用$vector$儲存,啟發式合併做到整體均攤$O(N\log N)$,現在變成了$O(N)$
你覺得這沒有差?
嘿嘿嘿
還是要做這個優化才能卡進時限喔XD

時間複雜度:$O(N\log^{2}N)$

code:
#include<cstdio>
#include<cassert>
#include<vector>
#include<algorithm>
using namespace std;
//void assert(bool valid){if(valid)return;for(;;)putchar('E');}
struct Node
{
    Node *ch[2];
    int sum,tag,idl,idr;
//    Node():ch{NULL,NULL},sum(0),tag(0),ids(new vector<int>()){}
}Node_BUFFER[2000000],*NEW;
int LINKED_LIST[100000];
Node *NewNode()
{
    NEW->ch[0]=NEW->ch[1]=NULL;
    NEW->sum=NEW->tag=0;
    NEW->idl=NEW->idr=-1;
    return NEW++;
}
void PutDown(Node *o,const int depth)
{
    if((1<<depth)&o->tag)swap(o->ch[0],o->ch[1]);
    for(int d=0;d<2;d++)if(o->ch[d])o->ch[d]->tag^=o->tag;
    o->tag=0;
}
int Sum(Node *o){return o?o->sum:0;}
void Maintain(Node *o)
{
    o->sum=Sum(o->ch[0])+Sum(o->ch[1]);
}
void Insert(Node* &o,const int depth,const int value,const int id)
{
    if(!o)o=NewNode();
    if(depth==-1)
    {
        o->sum=1;
        if(o->idl==-1)o->idl=o->idr=id;
        else
        {
            LINKED_LIST[id]=o->idl;
            o->idl=id;
        }
        return;
    }
    PutDown(o,depth);
    Insert(o->ch[((1<<depth)&value)>>depth],depth-1,value,id);
    Maintain(o);
}
void Merge(int &idl,int &idr,Node *a,Node *b)
{
    if(a->idl==-1||b->idl==-1)
    {
        if(a->idl==-1)swap(a,b);
        idl=a->idl,idr=a->idr;
    }
    else
    {
        LINKED_LIST[a->idr]=b->idl;
        idl=a->idl,idr=b->idr;
    }
}
Node *Merge(Node *a,Node *b,const int depth)
{
    if(!a||!b)return a?a:b;
    Node *ans=NewNode();
    if(depth==-1)ans->sum=(a->sum)|(b->sum),Merge(ans->idl,ans->idr,a,b);
    else
    {
        PutDown(a,depth),PutDown(b,depth);
        ans->ch[0]=Merge(a->ch[0],b->ch[0],depth-1);
        ans->ch[1]=Merge(a->ch[1],b->ch[1],depth-1);
        Maintain(ans);
    }
    return ans;
}
int GetSG(Node *o,const int depth,const int now)
{
    if(!o||depth==-1)return now;
    PutDown(o,depth);
    if(Sum(o->ch[0])<(1<<depth))return GetSG(o->ch[0],depth-1,now);
    else
    {
        assert(Sum(o->ch[1])<(1<<depth));
        return GetSG(o->ch[1],depth-1,now+(1<<depth));
    }
}
int N,COLOR[100000];
vector<int>ET[100000];
Node *GetTree(const int u,const int parent,int &allsg)
{
    vector<Node*>ch_trees;
    vector<int>ch_sgs;
    allsg=0;
    for(const int nxt:ET[u])if(nxt!=parent)
    {
        int ch_sg;
        ch_trees.push_back(GetTree(nxt,u,ch_sg));
        ch_sgs.push_back(ch_sg);
        allsg^=ch_sg;
    }
    Node *ans=NULL;
    for(int i=0;i<(int)ch_trees.size();i++)if(ch_trees[i])
    {
        ch_trees[i]->tag^=allsg^ch_sgs[i];
        ans=Merge(ans,ch_trees[i],17);
    }
    if(COLOR[u]==0)Insert(ans,17,allsg,u),allsg=GetSG(ans,17,0);
    return ans;
}
void GetIds(Node *o,vector<int>&ans)
{
    for(int depth=17;depth>=0;depth--)
    {
        PutDown(o,depth);
        o=o->ch[0],assert(o);
    }
    ans.clear();
    for(int cur=o->idl;;cur=LINKED_LIST[cur])
    {
        ans.push_back(cur);
        if(cur==o->idr)break;
    }
}
int main()
{
//    freopen("in.txt","r",stdin);
//    freopen("out.txt","w",stdout);
    while(scanf("%d",&N)==1)
    {
        NEW=Node_BUFFER;
        for(int i=0;i<N;i++)ET[i].clear();
        for(int i=0;i<N;i++)scanf("%d",&COLOR[i]);
        for(int i=0,a,b;i<N-1;i++)
        {
            scanf("%d%d",&a,&b),a--,b--;
            ET[a].push_back(b),ET[b].push_back(a);
        }
        int ans;
        Node *o=GetTree(0,-1,ans);
        ans=GetSG(o,17,0);
        if(ans==0)puts("-1");
        else
        {
            assert(o);
            vector<int>ans;
            GetIds(o,ans);
            sort(ans.begin(),ans.end());
            for(const int v:ans)printf("%d\n",v+1);
        }
    }
    return 0;
}

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