【LeetCode】111. Minimum Depth of Binary Tree

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.

【思路】

递归调用，注意判断树的深度应该到叶子节点，也就是左右子结点都为空的那个结点

/**
 * Definition for a binary tree node.
 * 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)
         return minDepth(root->right) +1;
        if(root->right == NULL)
        return minDepth(root->left) +1;
        return min(minDepth(root->left),minDepth(root->right))+1; 
    }
};