128 lines
2.6 KiB
C++
128 lines
2.6 KiB
C++
#include <iostream>
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#include <queue>
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#include <cstring>
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#define lson l,m,rt<<1
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#define rson m+1,r,rt<<1|1
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using namespace std;
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const int ma=1000010;
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const int inf=1<<25;
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int n;
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int c[ma<<2];
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int rc[ma];
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int add[ma<<2];
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int rrt;
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void pushup(int rt)
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{
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c[rt]=min(c[rt<<1],c[rt<<1|1]);
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}
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void pushdown(int rt,int m)
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{
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if(add[rt])
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{
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add[rt<<1]+=add[rt];
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add[rt<<1|1]+=add[rt];
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c[rt<<1]+=add[rt];
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c[rt<<1|1]+=add[rt];
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add[rt]=0;
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}
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}
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void build(int l,int r,int rt)
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{
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add[rt]=0;
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if(l==r)
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{
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scanf("%d",&c[rt]);
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return ;
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}
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int m=(l+r)>>1;
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build (lson);
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build (rson);
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pushup(rt);
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}
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int query(int l,int r,int rt)
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{
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if(l==r){rrt=rt;return l;}
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pushdown(rt,r-l+1);
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int m=(l+r)>>1;
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if(c[rt<<1]<=c[rt<<1|1])
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return query(lson);
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else return query(rson);
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}
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void update(int L,int R,int l,int r,int rt)
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{
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if(L<=l&&r<=R)
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{
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add[rt]--;
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c[rt]--;
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return ;
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}
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pushdown(rt,r-1+1);
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int m=(l+r)>>1;
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if(L<=m) update(L,R,lson);
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if(m<R)update(L,R,rson);
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pushup(rt);
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}
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void update2(int p,int l,int r,int rt)
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{
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if(l==r)
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{
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c[rt]=inf;
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return ;
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}
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int m=(l+r)>>1;
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if(p<=m)update2(p,lson);
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else update2(p,rson);
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pushup(rt);
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}
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int main()
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{
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while(scanf("%d",&n),n)
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{
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int id=0;
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int flag=0;
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build(1,n,1);
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queue <int> a;
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queue <int> b;
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while(a.size()+b.size()!=2*n)
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{
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int qq=query(1,n,1);
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if(c[rrt]<0)
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{
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flag=1;break;
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}
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if(c[rrt]==0)
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{
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a.push(qq);
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b.push(-qq);
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if(qq!=1)
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update(1,qq-1,1,n,1);
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update2(qq,1,n,1);
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}
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else
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{
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if(b.size()==0){flag=1;break;}
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int t=b.front();
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if(-t<n)
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update(-t+1,n,1,n,1);
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b.pop();
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a.push(t);
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}
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}
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if(flag)
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{
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printf("Impossible\n");
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}else{
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int d[200010];
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int i=0;
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while(a.size()!=0)
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{d[i++]=a.front();a.pop();}
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while(b.size()!=0)
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{d[i++]=b.front();b.pop();}
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for(i=2*n-1;i>=0;i--)
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printf("%d ",d[i]);
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puts("");
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}
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}
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return 0;
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}
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