[LeetCode] Minimum Depth of Binary Tree

int minDepth(TreeNode *root) {
	vector<TreeNode*> nodes;
	vector<int> depths;
	int min_depth = 0;
	if(root != NULL)
	{
		nodes.push_back(root);
		depths.push_back(1);
	}
	while(!nodes.empty())
	{
		TreeNode* cur_node = nodes.back();
		int cur_node_depth = depths.back();
		TreeNode* left_child  = cur_node->left;
		TreeNode* right_child = cur_node->right;
		nodes.pop_back();
		depths.pop_back();
		if(right_child != NULL)
		{
			nodes.push_back(right_child);
			int right_child_depth = cur_node_depth + 1;
			depths.push_back(right_child_depth);
		}
		if(left_child != NULL)
		{
			nodes.push_back(left_child);
			int left_child_depth = cur_node_depth + 1;
			depths.push_back(left_child_depth);
		}
		if(left_child == NULL && right_child == NULL)
		{
			if(min_depth == 0)
			{
				min_depth = cur_node_depth;
			}
			else if(cur_node_depth < min_depth)
			{
				min_depth = cur_node_depth;
			}            
		}
	}
	return min_depth;
}

參考Binary Tree Postorder Traversal遍歷方法