玩转二叉树

#include<cstdio>
#include<iostream>
#include<algorithm>
#include<string>
#include<queue>
#include<cmath>
#include<vector>
#include<cstdlib>
using namespace std;

#define long long ll
const int maxn  = 100 + 5;

int zhong[maxn],qian[maxn];
struct node
{
    int l,r;
}a[maxn];
int build(int la,int ra,int lb,int rb)
{
    if(la > ra)
        return 0;
    int rt = qian[lb];
    int posrt = la;
    while(zhong[posrt] != rt)
        posrt++;
    int l = posrt - la;
    a[rt].l = build(la,la + l - 1,lb + 1,lb + l);
    a[rt].r = build(posrt + 1,ra,lb + l + 1,rb);
    return rt;
}
void bfs(int x)
{
    queue<int>que;
    vector<int>vec;
    que.push(x);
    while(!que.empty())
    {
        int tmp = que.front();
        que.pop();
        if(tmp == 0)
            break;
        vec.push_back(tmp);
        if(a[tmp].r != 0)
            que.push(a[tmp].r);
        if(a[tmp].l != 0)
            que.push(a[tmp].l);
    }
    for(int i=0;i<vec.size();i++)
        printf("%d%c",vec[i],i == (vec.size() - 1) ? ‘\n‘ : ‘ ‘);
}
int main()
{
    int n;
    scanf("%d",&n);
    for(int i=1;i<=n;i++)
        scanf("%d",&zhong[i]);
    for(int i=1;i<=n;i++)
        scanf("%d",&qian[i]);
    build(1,n,1,n);
    int root = qian[1];
    bfs(root);
}