是有可能找到为O(n)时间给定阵列中的所有三胞胎? [英] is it possible to find all the triplets in the given array for the O (n) time?
问题描述
由于数字数组找到所有三胞胎满足给定条件。
Given an array of numbers find all such triplets that satisfy the given condition.
条件: A [1] - ;一个研究[J] LT;一个[K]
,其中 I< J<氏/ code>。
Condition: a[i] < a[j] < a[k]
where I < j < k
.
就可以解决O(n)时间这个问题?
it is possible to solve this problem in O (n) time?
这是不在家工作!
推荐答案
输出(最坏情况)的大小是一个下界复杂
The size of the output (worst case) is a lower bound on the complexity.
由于有可能为O(n ^ 3)这样的三胞胎,复杂性不能为O(n)。
Since there are possibly O(n^3) such triplets, the complexity cannot be O(n).
例如,如果阵列从低到高排序,你将有n个选择3个这样的三胞胎,它是N阶^ 3。
For example if the array is sorted from lowest to highest, you will have n choose 3 such triplets which is order of n^3.
如果这个问题指的是发现三胞胎的数量,这里是最有效的解决方案,我看到:
If the question refers to finding the number of triplets, here is the most efficient solution I saw:
<一个href=\"http://cs.stackexchange.com/questions/7409/count-unique-increasing-subsequences-of-length-3-in-on-log-n\">http://cs.stackexchange.com/questions/7409/count-unique-increasing-subsequences-of-length-3-in-on-log-n
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