1102 Invert a Binary Tree (25 分)难度: 一般 / 知识点: 树的建立 和 中/层序遍历

Posted 2021-12-16 辉小歌

https://pintia.cn/problem-sets/994805342720868352/problems/994805365537882112

#include<bits/stdc++.h>
using namespace std;
const int N=1e5+10;
map<int,int>l,r;
int n,root;
vector<int>a,b,backup;
void dfs(int u)

    if(l[u]) dfs(l[u]);
    backup.push_back(u);
    if(r[u]) dfs(r[u]);

void bfs(int u)

    queue<int>q; q.push(u);
    while(q.size())
    
        int t=q.front(); q.pop();
        a.push_back(t);
        if(l[t]) q.push(l[t]);
        if(r[t]) q.push(r[t]);
    

int main(void)

    cin>>n;
    for(int i=1;i<=n;i++)
    
        char a,b; cin>>a>>b;
        if(a!='-') r[i]=a-'0'+1;//统一从1开始便于处理
        if(b!='-') l[i]=b-'0'+1;
    
    for(int i=1;i<=n;i++) //因为不知道哪个是根节点所以都跑一遍，存结点数最多的
    
        backup.clear();
        dfs(i);
        if(backup.size()>b.size()) b=backup,root=i;
    
    bfs(root);
    for(int i=0;i<a.size();i++)
    
        if(i) cout<<" ";
        cout<<a[i]-1;
    
    cout<<"\\n";
    for(int i=0;i<b.size();i++)
    
        if(i) cout<<" ";
        cout<<b[i]-1;
    
    return 0;