题目描述

Given an array of integers, find out whether there are two distinct indices i and j in the array such that the difference between nums[i] and nums[j] is at most t and the difference between i and j is at most k.

分析

对于加入的元素，要能够在O(1)时间内查找，同时还要自动排序，维持一个k个元素的TreeSet。

代码

    public boolean containsNearbyAlmostDuplicate(int[] nums, int k, int t) {

        if (k < 1 || t < 0 || nums == null || nums.length < 2) {
            return false;
        }

        SortedSet<Long> set = new TreeSet<Long>();

        for (int j = 0; j < nums.length; j++) {

            SortedSet<Long> subSet = set.subSet((long) nums[j] - t,
                    (long) nums[j] + t + 1);

            // 集合不为空，则表示找到解
            if (!subSet.isEmpty()) {
                return true;
            }

            if (j >= k) {
                set.remove((long) nums[j - k]);
            }

            set.add((long) nums[j]);
        }

        return false;

    }