https://leetcode-cn.com/problems/contains-duplicate-iii/
https://leetcode-cn.com/problems/contains-duplicate-iii/solution/cjian-ji-dai-ma-by-orangeman-6/
class Solution {
public:
bool containsNearbyAlmostDuplicate(vector<int>& nums, int k, int t) {
set <long> s;
for (int i = 0; i < nums.size(); ++i) {
auto it = s.lower_bound(nums[i]-t);
if (it != s.end() && *it <= (long)(nums[i] + t)) return true;
if (i >= k + 1) s.erase(nums[i - k]);
}
return false;
}
};