LeetCode OJ：Minimum Depth of Binary Tree（二叉树的最小深度）

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.

求二叉树的最小深度，额，简单的递归而已，代码如下：

class Solution {
public:
    int minDepth(TreeNode* root) {
        if(root = NULL) return 0;
        int leftDep = minDepth(root->left);
        int rightDep = minDepth(root->right);
        if(leftDep == 0 && rightDep == 0) return 1;//叶子节点
        if(leftDep == 0) leftDep = INT_MAX;
        if(rightDep == 0) rightDep = INT_MAX;//中间节点
        return min(leftDep, rightDep) + 1; 
    }
};

java 版本的代码一样，与上面相同，代码如下所示：

/**
 * Definition for a binary tree node.
 * public class TreeNode {
 *     int val;
 *     TreeNode left;
 *     TreeNode right;
 *     TreeNode(int x) { val = x; }
 * }
 */
public class Solution {
    public int minDepth(TreeNode root) {
        if(root == null) 
            return 0;
        int leftDep = minDepth(root.left);
        int rightDep = minDepth(root.right);
        if(leftDep == 0 && rightDep == 0)
            return 1; //到达这里表明的是叶子节点
        if(leftDep == 0) leftDep = Integer.MAX_VALUE;
        if(rightDep == 0) rightDep = Integer.MAX_VALUE;
        return Math.min(leftDep, rightDep) + 1;       
    }
}