java - 深度以上尺寸和深度以下尺寸

Question

我是 Java 的初学者，我正在尝试编写代码来计算深度小于给定深度的节点数和深度大于给定深度的节点数。

public static int sizeAboveDepth(Node t, int k) {
    // TODO: Complete this method.
    if (t == null) {
      return 0;
    }
    if (t.key > k)
      return (sizeAboveDepth(t.left, k - 1) + sizeAboveDepth(t.right, k - 1) + 1);
    else {
      return sizeAboveDepth(t.left, k - 1) + sizeAboveDepth(t.right, k-1);
    }
  }

  // EXERCISE 6: The method "sizeBelowDepth" is described above.
  // The number of nodes in the tree "below" depth k (not including k)
  // include node n if depth(n) > k.
  public static int sizeBelowDepth(Node t, int k) {
    // TODO: Complete this method.
    if (t == null) {
      return 0;
    }
    if (t.key > k)
      return (sizeBelowDepth(t.left, k-1) + sizeBelowDepth(t.right, k-1) + 1);
    else {
      return sizeBelowDepth(t.left, k-1) + sizeBelowDepth(t.right, k-1);
    }
  }

所以有没有人可以帮我解决这个问题？我现在有点疯狂~~

Answer 1

public static int sizeAboveDepth(Node t, int depth, final int k) {
  if ( t != null && depth < k){
    return sizeAboveDepth( t.left, depth+1, k) + 
           sizeAboveDepth( t.right, depth+1, k) + 1;
  } else {
    return 0;
  }   
}

public static int sizeBelowDepth(Node t, int depth, final int k) {
  if (t == null) {
    return 0;
  }
  int below = sizeBelowDepth(t.left, depth+1, k) + 
              sizeBelowDepth(t.right, depth+1, k);
  if (depth > k){
    below++;
  }
  return below;
}