6-5 No Greater Than X in BST （20 分）

6-5 No Greater Than X in BST （20 分）

You are supposed to output, in decreasing order, all the elements no greater than X in a binary search tree T.

Format of function:

void Print_NGT( Tree T,  int X );

where Tree is defined as the following:

typedef struct TreeNode *Tree;
struct TreeNode {
    int Element;
    Tree  Left;
    Tree  Right;
};

The function is supposed to use Output(X) to print X.

Sample program of judge:

#include <stdio.h>
#include <stdlib.h>

typedef struct TreeNode *Tree;
struct TreeNode {
    int Element;
    Tree  Left;
    Tree  Right;
};

Tree BuildTree(); /* details omitted */
void Output( int X ); /* details omitted */

void Print_NGT( Tree T,  int X );

int main()
{
    Tree T;
    int X;

    T = BuildTree();
    scanf("%d", &X);
    Print_NGT( T, X );
    printf("End\n");

    return 0;
}

/* Your function will be put here */

Sample Output 1 (for the tree shown in Figure 1):

91 90 85 81 80 55 End

Sample Output 2 (for the tree shown in Figure 2):

End

作者: DS課程組

單位: 浙江大學

時間限制: 400 ms

內存限制: 64 MB

代碼長度限制: 16 KB

---

int a[100];
int i=0;

void pretravel(Tree T){
    if(!T)
        return;
    if (T->Left)
        pretravel(T->Left);
    a[i]=T->Element;
    i++;
    if (T->Right)
        pretravel(T->Right);
    return;
}

void Print_NGT( Tree T,  int X ){
    pretravel(T);
    for (int j=i-1; j>=0; j--) {
        if(a[j]<=X)
        printf("%d ",a[j]);
    }
}