[leetcode] 5. Minimum Depth of Binary Tree

二叉树基本功练习题，题目如下：

Given a binary tree, find its minimum depth.

The minimum depth is the number of nodes along the shortest path from the root node down to the nearest leaf node.

就是找最短的那条从根到叶，跟上一道题一样直接那递归上就行。解法如下：

/**
 * Definition for binary tree
 * struct TreeNode {
 *     int val;
 *     TreeNode *left;
 *     TreeNode *right;
 *     TreeNode(int x) : val(x), left(NULL), right(NULL) {}
 * };
 */
class Solution {
public:
	void minDepth(TreeNode *temp, int count, int &min)
	{
		if (temp != NULL)
		{
			if (temp->left == NULL && temp->right == NULL)
			{
				min = min > count ? count : min;
			}

			minDepth(temp->left, count + 1, min);
			minDepth(temp->right, count + 1, min);
		}
	}
	int minDepth(TreeNode *root) {
		if (root == NULL)
		{
			return 0;
		}
		int min = 2147483647;
		minDepth(root, 1, min);
		return min;
	}
};

就是这样，拿count来计数，然后把min的地址传参进去，每到底部叶子的时候判断一次大小。