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.
参考资料：
https://leetcode.com/discuss/38195/short-c-solution
http://www.cnblogs.com/easonliu/p/4544073.html
[LeetCode] Contains Duplicate III 包含重复值之三
原文：http://www.cnblogs.com/grandyang/p/4545261.html