函数题：Print the left subtree of X in BST

Given a binary search tree T, you are supposed to output all the elements in the left subtree of X, in *ascending order*.

### Format of functions:
c
void print_left_subtree( Tree T, int X );

where Tree is defined as:
c
typedef struct TreeNode *Tree;
struct TreeNode {
int element;
Tree left;
Tree right;
};


### Sample program of judge:
c
#include <stdio.h>
#include <stdlib.h>

typedef struct TreeNode *Tree;
struct TreeNode {
int element;
Tree left;
Tree right;
};

Tree build_tree(); /* details omitted */

void print_left_subtree(Tree T, int X);

int main()
{
Tree T;
int X;

T = build_tree();
scanf("%d", &X);
print_left_subtree(T, X);

return 0;
}

/* Your function(s) will be put here */


### Sample Input
in
7
90 80 91 55 70 85 92
80



### Sample Output:



<br/><br/>

For the sample above, your program should output:
out
55 70 end



For an empy tree, simply output:

empty tree



In case X is not found in T, output:

x not found



where the letter "x" is NOT the value of X.





答案：若无答案欢迎评论