1.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.
2.題目要求：求二叉樹的最小深度即最短路徑的節(jié)點個數(shù)摄杂。
3.方法：用遞歸的方法坝咐，深度優(yōu)先搜索DFS來完成。
4.代碼：
/**
Definition for binary tree
struct TreeNode {
int val;TreeNode *left;TreeNode *right;TreeNode(int x) : val(x), left(NULL), right(NULL) {}-
};
*/
class Solution {
public:
int minDepth(TreeNode *root) {
if (root == NULL) return 0;
if (root->left == NULL && root->right == NULL) return 1;if (root->left == NULL) return minDepth(root->right) + 1; else if (root->right == NULL) return minDepth(root->left) + 1; else return 1 + min(minDepth(root->left), minDepth(root->right));}
};
