CareerCup

if modular difference of depth(left) and depth(right) is greater than 1 then tree is not balanced.

int difference(int height1, int height2)
{
   if( height1 > height2)
      return height1 - height2;
   else 
      return height2 - height1;
}

int isBalancedBinaryTree(node *root)
{
   int x=0,y=0;

   if(root == NULL)
      return 0;
   x= depth(root->left);
   y= depth(root->right);

   printf("Left height =%d right height=%d\n", x, y);
   if(difference(depth(root->left),depth(root->right)) > 1)
      return(0);
   else 
      return 1;
}

‌boolean balance(node* T,int* h)
{
  if(T == null)
   {
     *h = 0;
     return true;
   }
   
   int lh,rh;
   bool lr = balance(T->left,&lh);
   bool rr = balance(T->right,&rh);

   if(mod(lh- rh)>1))
      return false;

   *h = lh+rh+1;
   return lr&rr ;
 
}

private static boolean isBalanced(TreeNode01 root) {
return ((maxDepth(root) - minDepth(root)) <= 1);
}

private static int maxDepth(TreeNode01 root) {
if (root == null) {
return -1;
}

return 1 + Math.max(maxDepth(root.left), maxDepth(root.right));
}

private static int minDepth(TreeNode01 root) {
if(root.right == null && root.left == null) {
return 0;
}
if(root.left == null && root.right != null) {
return 1 + minDepth(root.right);
}
if(root.right == null && root.left != null) {
return 1 + minDepth(root.left);
}
else {
return 1 + Math.min(minDepth(root.left), minDepth(root.right));
}

}

There are quite a few methods to judge the balance of tree structure. Like AVL, red-black and so on.