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102 Binary Tree Level Order Traversal.c
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102 Binary Tree Level Order Traversal.c
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/**
* Definition for a binary tree node.
* struct TreeNode {
* int val;
* struct TreeNode *left;
* struct TreeNode *right;
* };
*/
#define QUEUE_SIZE 2000
typedef struct
{
struct TreeNode * queue_arr[QUEUE_SIZE];
int level_arr[QUEUE_SIZE];
int rear;
int front;
}Queue;
int isQueueEmpty(Queue * tmp_queue)
{
if(tmp_queue->front == -1)
return 1;
else
return 0;
}
int isQueueFull(Queue * tmp_queue)
{
if(tmp_queue->rear == QUEUE_SIZE-1)
return 1;
else
return 0;
}
void enqueue(Queue * tmp_queue, struct TreeNode * element, int level)
{
if(isQueueFull(tmp_queue))
return;
tmp_queue->queue_arr[++(tmp_queue->rear)] = element;
tmp_queue->level_arr[tmp_queue->rear] = level;
if(tmp_queue->front == -1)
{
tmp_queue->front = 0;
}
return;
}
struct TreeNode * dequeue(Queue * tmp_queue, int * level)
{
if(isQueueEmpty(tmp_queue))
return NULL;
struct TreeNode * ret_val = tmp_queue->queue_arr[tmp_queue->front];
*level = tmp_queue->level_arr[tmp_queue->front];
if(tmp_queue->front == tmp_queue->rear)
{
tmp_queue->front = -1;
tmp_queue->rear = -1;
}
else
{
++(tmp_queue->front);
}
return ret_val;
}
int height(struct TreeNode * root)
{
if(root == NULL)
return 0;
int left_ht = height(root->left);
int right_ht = height(root->right);
if(left_ht >= right_ht)
return (left_ht + 1);
else
return (right_ht + 1);
}
/**
* Return an array of arrays of size *returnSize.
* The sizes of the arrays are returned as *returnColumnSizes array.
* Note: Both returned array and *columnSizes array must be malloced, assume caller calls free().
*/
int** levelOrder(struct TreeNode* root, int* returnSize, int** returnColumnSizes)
{
Queue tmp_queue;
tmp_queue.rear = -1;
tmp_queue.front = -1;
int ht_of_tree = height(root);
int ** ret_ptr = (int **)malloc(sizeof(int *) * ht_of_tree);
int ret_ptr_index = -1;
*returnColumnSizes = (int *)malloc(sizeof(int) * ht_of_tree);
int index = 0;
*returnSize = ht_of_tree;
if(root == NULL)
{
*returnSize = 0;
return ret_ptr;
}
struct TreeNode * tmp_ptr = root;
int prev_level = 0;
int current_level = 1;
int * arr = NULL;
int arr_index = 0;
enqueue(&tmp_queue, tmp_ptr, current_level);
while(!isQueueEmpty(&tmp_queue))
{
tmp_ptr = dequeue(&tmp_queue, ¤t_level);
if(current_level != prev_level)
{
if(tmp_ptr != root)
{
*(*returnColumnSizes + index) = arr_index;
index++;
}
arr_index = 0;
arr = (int *)malloc(sizeof(int) * 1);
arr[arr_index++] = tmp_ptr->val;
ret_ptr[++ret_ptr_index] = arr;
}
else if(current_level == prev_level)
{
arr = realloc(arr, sizeof(int) * (arr_index+1));
arr[arr_index++] = tmp_ptr->val;
ret_ptr[ret_ptr_index] = arr;
}
if(tmp_ptr->left != NULL)
{
enqueue(&tmp_queue, tmp_ptr->left, current_level+1);
}
if(tmp_ptr->right != NULL)
{
enqueue(&tmp_queue, tmp_ptr->right, current_level+1);
}
prev_level = current_level;
}
*(*returnColumnSizes + index) = arr_index;
return ret_ptr;
}