BZOJ1078: [SCOI2008]斜堆

#include<cstring>
#include<iostream>
#include<algorithm>
#include<cstdlib>
#include<cstdio>
#include<cmath>
#include<queue>
#define rep(i,l,r) for (int i=l;i<=r;i++)
#define down(i,l,r) for (int i=l;i>=r;i--)
#define clr(x,y) memset(x,y,sizeof(x))
#define maxn 2005
#define eps 1e-3
#define ll long long
#define inf (1LL<<50)
using namespace std;
int fa[maxn],l[maxn],r[maxn],ans[maxn],n,tot,root;
int read(){
    int x=0,f=1; char ch=getchar();
    while (!isdigit(ch)) {if (ch==‘-‘) f=-1; ch=getchar();}
    while (isdigit(ch)) {x=x*10+ch-‘0‘; ch=getchar();}
    return x*f;
}
void solve(){
    int x=root;
    while (r[x]!=-1) x=l[x];
    int t=l[x];
    if (t!=-1&&l[t]==-1&&r[t]==-1) x=t;
    ans[++tot]=x;
    if (x==root) root=l[root];
    int f=fa[x];
    if (f!=-1) l[f]=l[x],fa[l[f]]=f;
    while (f!=-1) swap(l[f],r[f]),f=fa[f]; 
}
int main(){
    n=read();
    fa[0]=-1;
    clr(l,-1); clr(r,-1);
    rep(i,1,n) {
        int x=read(); 
        if (x>=100) fa[i]=x-100,r[x-100]=i;
        else fa[i]=x,l[x]=i; 
    }
    rep(i,0,n) solve();
    while (tot) printf("%d ",ans[tot--]);
    return 0;
}