思路

中序遍历建树，运用递归

C++ 代码

#include <iostream>
#include <algorithm>
#define MAX 1000
using namespace std;
int value[MAX], preOrder[MAX + 1], k = 0;
int N;

void dfs(int x) {
    if (x > N) return;
    dfs(x * 2);
    preOrder[x] = value[k++];
    dfs(x * 2 + 1);
}

int main() {
    cin >> N;
    for (int i = 0; i < N; i++) {
        cin >> value[i];
    }
    sort(value, value + N);
    dfs(1);
    printf("%d", preOrder[1]);
    for (int i = 2; i <= N; i++) {
        printf(" %d", preOrder[i]);
    }
    return 0;
}