[111] Minimum Depth of Binary Tree

嗯 ....好吧其實我覺得我現在無法思考中  囧

找最小的深度，和找最深的差別在於，

當深度是0 (就沒有child的時候）需要return 另一個child的長度

舉例為，一個root 一路往右長，root-> left == NULL 的情況

然後就降了?!(?!)

/**

* Definition for a binary tree node.

* struct TreeNode {

* int val;

* struct TreeNode *left;

* struct TreeNode *right;

* };

*/

int depth(struct TreeNode* root, int h)

{

int ret=0;

if (root ==NULL )

return h;

int left = depth(root->left, h+1);

int right = depth(root->right, h+1);

//printf("h=%d, %d %d\n",h, left, right);

if (left == h+1)

ret = right;

else if (right == h+1)

ret = left;

else

ret = (left<right)? left:right;

return ret;

}

int minDepth(struct TreeNode* root) {

return depth(root, 0);

}