越靠近叶子越优先删掉
#include <iostream>
#include <vector>
#include <cstdio>
using namespace std;
int n, uu, hea[200005], cnt, deg[200005], fa[200005];
bool vis[200005];
vector<int> shu;
vector<int> ans;
struct Edge{
int too, nxt;
}edge[400005];
void add_edge(int fro, int too){
edge[++cnt].nxt = hea[fro];
edge[cnt].too = too;
hea[fro] = cnt;
}
void dfs(int x, int f){
shu.push_back(x);
fa[x] = f;
for(int i=hea[x]; i; i=edge[i].nxt){
int t=edge[i].too;
if(t!=f) dfs(t, x);
}
}
void shanchu(int x){
vis[x] = true;
ans.push_back(x);
for(int i=hea[x]; i; i=edge[i].nxt){
int t=edge[i].too;
deg[t]--;
if(t!=fa[x] && !vis[t]){
if(deg[t]%2==0)
shanchu(t);
}
}
}
int main(){
cin>>n;
for(int i=1; i<=n; i++){
scanf("%d", &uu);
if(!uu) continue;
add_edge(uu, i);
add_edge(i, uu);
deg[i]++; deg[uu]++;
}
dfs(1, 0);
for(int i=shu.size()-1; i>=0; i--){
int x=shu[i];
if(/*vis[x] ||*/deg[x]&1) continue;
shanchu(x);
}
if(ans.size()!=n) printf("NO\n");
else{
printf("YES\n");
for(auto i:ans) printf("%d\n", i);
}
return 0;
}
原文地址:https://www.cnblogs.com/poorpool/p/8899069.html
时间: 2024-11-09 13:47:45