LeetCode 220. Contains Duplicate III

class Solution {
public:
    bool containsNearbyAlmostDuplicate(vector<int>& nums, int k, int t) {
        set<long> counter;
        
        for(int i = 0;i < nums.size() ;i++){
            if (counter.lower_bound((long)nums[i]-(long)t) != counter.end() && *counter.lower_bound((long)nums[i]-(long)t) <= (long)nums[i]+(long)t )
            return true;
            else{
                counter.insert(nums[i]);
            }
            if(counter.size() >= k+1){
                counter.erase((long)nums[i-k]);
            }
        }
        
        return false;

    }
};