1099. Build A Binary Search Tree

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

程序代码：

#include<stdio.h>
#include<stdlib.h>
#define MAX 100
typedef struct
{
    int data;
    int left;
    int right;
}node;
typedef struct
{
    node value[MAX];
    int top;
    int bom;
}queue;
void initQueue(queue* s);
void push(queue* s,node tmp);
node pop(queue* s);
void layerPrint(node a[],int len);
int isEmptyQueue(queue*s);
int num[MAX];
int k=0;
int comp(const void* a,const void* b);
void inOrderVisit(node*p,int* num);
node a[MAX];
int main()
{   
    int num[MAX];
    int n,i;
    int cnt;
    scanf("%d",&n);
    for(i=0;i<n;i++)
    {
        scanf("%d%d",&a[i].left,&a[i].right);
    }
    for(i=0;i<n;i++)
    {
        scanf("%d",&num[i]);
    }
    qsort(num,n,sizeof(int),comp);
        inOrderVisit(&a[0],num);
    layerPrint(a,n);
    return 0;
}
void inOrderVisit(node*p,int* num)      //中序遍历填充节点值
{

    if(p->left!=-1)
        inOrderVisit(&a[p->left],num);
    p->data = num[k++];
    if(p->right!=-1)
        inOrderVisit(&a[p->right],num);
    return ;
}
void layerPrint(node a[],int len)       //层序遍历打印节点值
{
    int count=0;
    queue q;
    node p;
    initQueue(&q);
    push(&q,a[0]);
    while(q.top!=q.bom)
    {
        p = pop(&q);
        printf("%d",p.data);
        count++;
        if(count!=len)
            putchar(' ');
        if(p.left!=-1)  
            push(&q,a[p.left]);
        if(p.right!=-1)
            push(&q,a[p.right]);
    }
}
int comp(const void* a,const void* b)
{
    return *(int*)a -*(int*)b;
}
//队列的相关操作
void initQueue(queue* s)
{
    s->top = 0;
    s->bom = 0;
}
void push(queue* s,node tmp)
{
    s->value[s->top]=tmp;
    s->top++;
}
node pop(queue* s)
{
    node tmp ;
    tmp = s->value[s->bom];
    s->bom++;
    return tmp;
}
int isEmptyQueue(queue*s)
{
    if(s->top==s->bom)
        return 1;
    return 0;
}