Level-order Traversal（c语言函数指针样例）

Write a routine to list out the nodes of a binary tree in “level-order”. List the root, then nodes at depth 1, followed by nodes at depth 2, and so on. You must do this in linear time.
Format of functions:

void Level_order ( Tree T, void (*visit)(Tree ThisNode) );

where void (*visit)(Tree ThisNode) is a function that handles ThisNode being visited by Level_order, and Tree is defined as the following:

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

Sample program of judge:

#include <stdio.h>#include <stdlib.h>#define MaxTree 10 /* maximum number of nodes in a tree */typedef int ElementType;typedef struct TreeNode *Tree;struct TreeNode {    ElementType Element;    Tree  Left;    Tree  Right;};Tree BuildTree(); /* details omitted */void PrintNode( Tree NodePtr ){   printf(" %d", NodePtr->Element);}void Level_order ( Tree T, void (*visit)(Tree ThisNode) );int main(){    Tree T = BuildTree();    printf("Level-order:");    Level_order(T, PrintNode);    return 0;}/* Your function will be put here */

Sample Output (for the tree shown in the figure):

Level-order: 3 5 6 1 8 10 9

代码：

void Level_order ( Tree BT,void (*visit)(Tree ThisNode)){    if(BT == NULL)return;    struct TreeNode *queue[100];    int head,tail;    head = tail = 0;    queue[tail++] = BT;    while(head!=tail)    {        (*visit)(queue[head]);        if(queue[head]->Left!=NULL)queue[tail++] = queue[head]->Left;        if(queue[head]->Right!=NULL)queue[tail++] = queue[head]->Right;        head++;    }}