[抄题]:
Given an array of integers, find out whether there are two distinct indices i and j in the array such that the absolute difference between nums[i] and nums[j] is at most t and the absolute difference between i and j is at most k.
Example 1:
Input: nums = [1,2,3,1], k = 3, t = 0
Output: true
Example 2:
Input: nums = [1,0,1,1], k = 1, t = 2
Output: true
Example 3:
Input: nums = [1,5,9,1,5,9], k = 2, t = 3
Output: false
[暴力解法]:
时间分析:
空间分析:
[优化后]:
时间分析:
空间分析:
[奇葩输出条件]:
[奇葩corner case]:
bucket值可能很小,所以用 让分子变大。
- Integer.MIN_VALUE
[思维问题]:
以为2个指针,没想到果然有技巧
[英文数据结构或算法,为什么不用别的数据结构或算法]:
水桶排序的精髓在于容量恒定,重复出现的放在下一个水桶。此题要求数字差值恒定,所以可以用水桶排序。
做法:/容量即可。类似取余数。
[一句话思路]:
差值不超过t, 而且越近越好。在k范围内的bucket值重复出现肯定可以,相邻的检查一下也可以。
[输入量]:空: 正常情况:特大:特小:程序里处理到的特殊情况:异常情况(不合法不合理的输入):
[画图]:
[一刷]:
- map里存的是对象,变量类型都是大写开头。只能用put方法。其他一般的变量类型用小写开头即可。
long remappedNum = (long) nums[i] - Integer.MIN_VALUE;每个变量都要改成long
- 求map整个一坨的方法是:
if (map.keySet().size() > k)
[二刷]:
long型放在分母时,要加括号
/ ((long)t + 1);
[三刷]:
[四刷]:
[五刷]:
[五分钟肉眼debug的结果]:
nums[i - k] 要不要-1 自己试试就行了,也是debug的一个重点
[总结]:
水桶排序要求不能重复。做法:/容量即可。类似取余数。
[复杂度]:Time complexity: O(n) Space complexity: O(n)
[算法思想:迭代/递归/分治/贪心]:
[关键模板化代码]:
[其他解法]:
[Follow Up]:
[LC给出的题目变变变]:
[代码风格] :
[是否头一次写此类driver funcion的代码] :
[潜台词] :
class Solution {
public boolean containsNearbyAlmostDuplicate(int[] nums, int k, int t) {
//cc
if (nums == null || nums.length == 0) return false;
if (k < 1 || t < 0) return false; //ini: HashMap, bucket
HashMap<Long, Long> map = new HashMap<>(); //for loop: judge as true in 3 cases, add(bucket, value) to map while maintain k
for (int i = 0; i < nums.length; i++) {
long appendedNum = (long)nums[i] - Integer.MIN_VALUE;
long bucket = appendedNum / ((long)t + 1); //judge as true in 3 cases
if (map.containsKey(bucket) ||
(map.containsKey(bucket - 1) && Math.abs(appendedNum - map.get(bucket - 1)) <= t) ||
(map.containsKey(bucket + 1) && Math.abs(map.get(bucket + 1) - appendedNum) <= t)) return true; //while maintain k numbers in the map
if (map.entrySet().size() >= k) {
long lastBucket = ((long)nums[i - k] - Integer.MIN_VALUE) / ((long)t + 1);
map.remove(lastBucket);
} //put to map
map.put(bucket, appendedNum);
} return false;
}
}