L2-011. 玩转二叉树

题目链接：L2-011. 玩转二叉树

和之前的题一样，只需要改动一点。

#include <iostream>
#include <cstdio>
#include <algorithm>
#include <cstring>
#include <vector>
#include <queue>
using namespace std;
const int maxn = 1e3+5;
int a[maxn];
int b[maxn];
int floor1[maxn];
int tr[maxn<<2];
int retr[maxn<<2];
int n;
void build(int x,int al,int ar,int bl,int br)
{
    if(ar<al||br<bl) return;
    if(al == ar)
    {
        tr[x] = a[al];
        return;
    }
    for(int i = 1; i<=n; i++)
    {
        if(a[i]==b[bl])
        {
            tr[x] = a[i];
            build(2*x,i+1,ar,bl+i-al+1,br);   //只需要将之前的代码上下两句调换即可。
            build(2*x+1,al,i-1,bl+1,bl+i-al);


            break;
        }
    }
}

void bfs(int x)  //按层序遍历
{
    queue<int> q;
    q.push(x);
    int ans = 1;
    while(!q.empty())
    {
        int y = q.front();
        q.pop();
        if(tr[y]==0) continue;
        floor1[ans++] = tr[y];
        q.push(2*y);
        q.push(2*y+1);
    }
}
int main()
{
    memset(tr,0,sizeof(tr));
    scanf("%d",&n);
    for(int i = 1; i<=n; i++)
    {
        scanf("%d",&a[i]);
    }
    for(int i = 1; i<=n; i++)
    {
        scanf("%d",&b[i]);
    }
    build(1,1,n,1,n);
    retr[1] = tr[1];
    bfs(1);
    for(int i = 1; i<n; i++) printf("%d ",floor1[i]);
    printf("%d
",floor1[n]);
    return 0;
}