public boolean IsBalanced_Solution(TreeNode root) {
return getDepth(root)!=-1;
}
private int getDepth(TreeNode root){
if(root==null) return 0;
int left=getDepth(root.left);
if(left==-1) return -1;
int right=getDepth(root.right);
if(right==-1) return -1;
return Math.abs(left-right)>1?-1:1+Math.max(left,right);
}
}