1099. Build A Binary Search Tree (30)-蒲公英云

1099. Build A Binary Search Tree (30)

向右看齐 2022-05-30 03:42 262阅读 0赞

A Binary Search Tree (BST) is recursively defined as a binary tree which has the following properties:

The left subtree of a node contains only nodes with keys less than the node’s key.The right subtree of a node contains only nodes with keys greater than or equal to the node’s key.Both the left and right subtrees must also be binary search trees.

Given the structure of a binary tree and a sequence of distinct integer keys, there is only one way to fill these keys into the tree so that the resulting tree satisfies the definition of a BST. You are supposed to output the level order traversal sequence of that tree. The sample is illustrated by Figure 1 and 2.

Input Specification:

Each input file contains one test case. For each case, the first line gives a positive integer N (<=100) which is the total number of nodes in the tree. The next N lines each contains the left and the right children of a node in the format “left_index right_index”, provided that the nodes are numbered from 0 to N-1, and 0 is always the root. If one child is missing, then -1 will represent the NULL child pointer. Finally N distinct integer keys are given in the last line.

Output Specification:

For each test case, print in one line the level order traversal sequence of that tree. All the numbers must be separated by a space, with no extra space at the end of the line.

Sample Input:

9
1 6
2 3
-1 -1
-1 4
5 -1
-1 -1
7 -1
-1 8
-1 -1
73 45 11 58 82 25 67 38 42

Sample Output:

58 25 82 11 38 67 45 73 42

题目大意：

代码：

#include<stdio.h>
#include<algorithm>
#include<queue>
using namespace std;
struct node
{
    int data;
    int lchild,rchild;
}tree[110];
int arr[110];
int num=0;
void midtraverl(int index)
{
    if(index!=-1)
    {
       midtraverl(tree[index].lchild);
       tree[index].data=arr[num++];
       midtraverl(tree[index].rchild);
    }
}
void leveltraverl(int index)
{
    queue<struct node> q;
    q.push(tree[index]);
    int flag=0;
    while(!q.empty())
    {
        struct node tmp=q.front();
        q.pop();
        if(tmp.lchild!=-1)
        q.push(tree[tmp.lchild]);
        if(tmp.rchild!=-1)
        q.push(tree[tmp.rchild]);
        if(flag==0)
        {
            printf("%d",tmp.data);
            flag=1;
        }
        else
        {
            printf(" %d",tmp.data);
        }
    }
}
int main()
{
    int i,j,n,m,k,t;
    scanf("%d",&n);
    for(i=0;i<n;i++)
    {
       scanf("%d %d",&tree[i].lchild,&tree[i].rchild);
    }
    for(i=0;i<n;i++)
    {
        scanf("%d",&arr[i]);
    }
    sort(arr,arr+n);
    midtraverl(0);
    leveltraverl(0);
    return 0;
}