A1167 Cartesian Tree（30分）PAT甲级 (Advanced Level) Practice（C++）满分题解【最小堆+构建树+层序遍历】

A Cartesian tree is a binary tree constructed from a sequence of distinct numbers. The tree is heap-ordered, and an inorder traversal returns the original sequence. For example, given the sequence { 8, 15, 3, 4, 1, 5, 12, 10, 18, 6 }, the min-heap Cartesian tree is shown by the figure.

Your job is to output the level-order traversal sequence of the min-heap Cartesian tree.

Input Specification:

Each input file contains one test case. Each case starts from giving a positive integer N (≤30), and then N distinct numbers in the next line, separated by a space. All the numbers are in the range of int.

Output Specification:

For each test case, print in a line the level-order traversal sequence of the min-heap Cartesian tree. All the numbers in a line must be separated by exactly one space, and there must be no extra space at the beginning or the end of the line.

Sample Input:

10
8 15 3 4 1 5 12 10 18 6

Sample Output:

1 3 5 8 4 6 15 10 12 18

 

代码如下：

#include
#include
#include
using namespace std;
const int MAX=0x3fffffff;
struct Node{
    int data;
    Node *left,*right;
}*tree;
vector nodelist;
Node* check(int low,int high)
{
    if(low<0||highdata=nodelist[min];
    newtree->left=check(low,min-1);
    newtree->right=check(min+1,high);
    return newtree;
}
int main()
{
    int n;
    cin>>n;
    for(int i=0;i>index;
        nodelist.push_back(index);
    }
    tree=check(0,n-1);
    int flag=0;
    queue q;
    q.push(tree);
    while(!q.empty()){
        Node *t=q.front();
        if(flag==1)cout<<" ";//只有第一个数前面不要输出空格
        else flag=1;
        cout<data;
        if(t->left)q.push(t->left);
        if(t->right)q.push(t->right);
        q.pop();
    }
    return 0;
}

运行结果如下：