1099 build a binary search tree (30 points)

Answer key

Good question ！！！
If I had done it before the ladder race last year It's really a good question
This question is the same as last year's ladder L2 The search tree There are similar places
I didn't make much achievements last year I thought that question could be withdrawn
It didn't turn out to be , According to a traversal sequence given by him I'm going through it again , Fill it in with this
This problem is given the template of binary tree , That question is almost given to
because That question is about a complete binary tree
So it's like giving

really · Answer key ： In the properties of binary search tree , The middle order traversal sequence is sequential
So the data that will be given , Sort , Is the middle order sequence .
so , Know the appearance of middle order sequence and binary tree , Then we can get the whole binary tree
The resulting process is a basic tree traversal

#include <iostream>
#include <queue>
#include <algorithm>
using namespace std;
const int n = 110;
int N;
int a[n], l[n], r[n], d[n];
int ind;
void build(int k)
{
    
    if (k == -1)
        return;
    build(l[k]);
    d[k] = a[ind++];
    build(r[k]);
}
void bfs()
{
    
    queue<int> q;
    q.push(0);
    while (!q.empty())
    {
    
        int x = q.front();
        q.pop();
        if (x != 0)
            cout << " ";
        cout << d[x];
        // cout << x << endl;
        if (l[x] != -1)
            q.push(l[x]);
        if (r[x] != -1)
            q.push(r[x]);
    }
}
int main()
{
    
    cin >> N;
    int x, y;
    for (int i = 0; i < N; i++)
    {
    
        cin >> x >> y;
        l[i] = x;
        r[i] = y;
    }
    for (int i = 0; i < N; i++)
        cin >> a[i];
    sort(a, a + N);
    build(0);
    bfs();
    return 0;
}