'''

public int minDepth(TreeNode root) {

if (null == root) {

return 0;

}

int left = minDepth(root.left);
int right = minDepth(root.right);
if (left == 0 || right == 0) {
return Math.max(left, right) + 1;
} else {
return Math.min(left, right) + 1;
}
}

'''