15算法课程 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.

solution:

本题思路递归，为了求最小值，那么在递归返回时只要返回左右子树的的较小值即可，但是要注意特殊情况即存在左或右子树不存在的情况，此时递归返回值要返回左右子树较大的值。

code:

class Solution {public:    int minDepth(TreeNode* root) {        if(root==NULL)            return 0;        int leftDepth = minDepth(root->left);        int rightDepth = minDepth(root->right);        if(rightDepth==0||leftDepth==0)            return max(leftDepth,rightDepth)+1;        else            return min(leftDepth,rightDepth)+1;    }};