-
- 两数之和 IV - 输入 BST
public List<int> Go(TreeNode root)
{
List<int> list = new List<int>();
if (root == null) return list;
list.AddRange(Go(root?.left));
list.Add(root.val);
list.AddRange(Go(root?.right));
return list;
}
public bool FindTarget(TreeNode root, int k)
{
List<int> list = Go(root);
for (int i = 0; i < list.Count; i++)
{
for (int j = i + 1; j < list.Count; j++)
{
if (list[i] + list[j] == k)
{
return true;
}
}
}
return false;
}
-
- 位1的个数
public int HammingWeight(uint n)
{
string k = Convert.ToString(n, 2);
return k.Where(item => item == '1').Count();
}