[IOI2018] seats 排座位

[IOI2018] seats 排座位

IOI2018题解

压缩状态思想很不错的

每次把原来的贡献减掉，新来的再加上

最多涉及10个点

注意：

1.去重

2.下标从0开始

3.线段树初始的最小值个数都是r-l+1

代码：

#include<bits/stdc++.h>
#define reg register int
#define il inline
#define mid ((l+r)>>1)
#define numb (ch^'0')
using namespace std;
typedef long long ll;
il void rd(int &x){
    char ch;x=;bool fl=false;
    while(!isdigit(ch=getchar()))(ch=='-')&&(fl=true);
    for(x=numb;isdigit(ch=getchar());x=x*+numb);
    (fl==true)&&(x=-x);
}
namespace Miracle{
const int N=+;
const int inf=0x3f3f3f3f;
int id[N],vis[N],sta[N],top;
int pos[N][];
int n,m,q;
int num(int x,int y){
    return (x-)*m+y;
}
struct tr{
    int mi,cnt;
    int mx;
    int ad;
}t[*N];
void pushup(int x){
    t[x].mi=min(t[x<<].mi,t[x<<|].mi);
    t[x].mx=max(t[x<<].mx,t[x<<|].mx);
    t[x].cnt=t[x<<].cnt*(t[x<<].mi==t[x].mi)+t[x<<|].cnt*(t[x<<|].mi==t[x].mi);
}
void pushdown(int x){
    if(!t[x].ad) return;
    t[x<<].ad+=t[x].ad;
    t[x<<].mi+=t[x].ad;
    t[x<<].mx+=t[x].ad;
    t[x<<|].ad+=t[x].ad;
    t[x<<|].mi+=t[x].ad;
    t[x<<|].mx+=t[x].ad;

    t[x].ad=;
}
void build(int x,int l,int r){
    if(l==r){
        t[x].cnt=;return;
    }
    build(x<<,l,mid);
    build(x<<|,mid+,r);
    pushup(x);
}
void add(int x,int l,int r,int L,int R,int c){
    if(L<=l&&r<=R){
        t[x].ad+=c;
        t[x].mi+=c;
        t[x].mx+=c;
        if(t[x].mi==t[x].mx) t[x].cnt=r-l+;
        return;
    }
    pushdown(x);
    if(L<=mid) add(x<<,l,mid,L,R,c);
    if(mid<R) add(x<<|,mid+,r,L,R,c);
    pushup(x);
}
int mv[][]={{+,},{-,},{,+},{,-}};
void wrk1(int x,int y,int c){
    //cout<<" x y "<<x<<" "<<y<<" c "<<c<<endl;
    int mi=inf,cmi=inf;
    for(reg i=;i<;++i){
        int dx=x+mv[i][],dy=y+mv[i][];
        if(dx>=&&dx<=n&&dy>=&&dy<=m){
            if(id[num(dx,dy)]<mi){
                cmi=mi;mi=id[num(dx,dy)];
            }else cmi=min(cmi,id[num(dx,dy)]);
        }
    }

    if(cmi<=id[num(x,y)]-) {
        //cout<<" x y "<<x<<" "<<y<<" : "<<mi<<" "<<cmi<<endl;
        add(,,n*m,cmi,id[num(x,y)]-,c);
    }
}
void wrk2(int x,int y,int c){
    int mi=n*m+;
    int dx=x-,dy=y;
    if(dx>=&&dx<=n&&dy>=&&dy<=m){
        mi=min(mi,id[num(dx,dy)]);
    }
    dx=x,dy=y-;
    if(dx>=&&dx<=n&&dy>=&&dy<=m){
        mi=min(mi,id[num(dx,dy)]);
    }
    //cout<<" x y "<<x<<" "<<y<<" mimimi "<<mi<<endl;
    if(id[num(x,y)]<=mi-) add(,,n*m,id[num(x,y)],mi-,c);
}
void sol(int x,int y,int c){
    //cout<<" sol "<<x<<" "<<y<<" c "<<c<<endl;
    if(!vis[num(x,y)]) {
        sta[++top]=num(x,y);
        vis[num(x,y)]=;
        wrk1(x,y,c);wrk2(x,y,c);
    }
    for(reg i=;i<;++i){
        int dx=x+mv[i][],dy=y+mv[i][];
        if(dx>=&&dx<=n&&dy>=&&dy<=m&&!vis[num(dx,dy)]){
            vis[num(dx,dy)]=;
            sta[++top]=num(dx,dy);
            wrk1(dx,dy,c);wrk2(dx,dy,c);
        }
    }
}
int main(){
    rd(n);rd(m);rd(q);
    build(,,n*m);
    int x,y;
    for(reg i=;i<=n*m;++i){
        rd(x);rd(y);
        ++x;++y;
        pos[i][]=x;pos[i][]=y;
        id[num(x,y)]=i;
    }
    for(reg i=;i<=n;++i){
        for(reg j=;j<=m;++j){
            wrk1(i,j,);
            wrk2(i,j,);
        }
    }
    //cout<<t[1].mi<<" "<<t[1].mx<<" "<<t[1].cnt<<endl;
    int A,B;
    while(q--){
        rd(A);rd(B);
        ++A;++B;
        top=;

        x=pos[A][],y=pos[A][];
        sol(x,y,-);
        x=pos[B][],y=pos[B][];
        sol(x,y,-);

        while(top) vis[sta[top--]]=;
        swap(id[num(pos[A][],pos[A][])],id[num(pos[B][],pos[B][])]);
        swap(pos[A][],pos[B][]);
        swap(pos[A][],pos[B][]);

        x=pos[A][],y=pos[A][];
        sol(x,y,);
        x=pos[B][],y=pos[B][];
        sol(x,y,);

        while(top) vis[sta[top--]]=;

        int ans=;
        if(t[].mi==) ans=t[].cnt;
        printf("%d\n",ans);
    }
    return ;
}

}
signed main(){
    Miracle::main();
    return ;
}

/*
   Author: *Miracle*
   Date: 2019/2/10 17:53:31
*/