MaxProductOfThree

Maximize A[P] A[Q] A[R] for any triplet (P, Q, R).

A non-empty array A consisting of N integers is given. The product of triplet (P, Q, R) equates to A[P] A[Q] A[R] (0 ≤ P < Q < R < N).

For example, array A such that:

A[0] = -3 A[1] = 1 A[2] = 2 A[3] = -2 A[4] = 5 A[5] = 6 contains the following example triplets:

(0, 1, 2), product is −3 1 2 = −6 (1, 2, 4), product is 1 2 5 = 10 (2, 4, 5), product is 2 5 6 = 60 Your goal is to find the maximal product of any triplet.

Write a function:

func Solution(A []int) int

that, given a non-empty array A, returns the value of the maximal product of any triplet.

For example, given array A such that:

A[0] = -3 A[1] = 1 A[2] = 2 A[3] = -2 A[4] = 5 A[5] = 6 the function should return 60, as the product of triplet (2, 4, 5) is maximal.

Write an efficient algorithm for the following assumptions:

N is an integer within the range [3..100,000]; each element of array A is an integer within the range [−1,000..1,000]. Copyright 2009–2021 by Codility Limited. All Rights Reserved. Unauthorized copying, publication or disclosure prohibited.

題目大意

給一整數陣列A，找出陣列中任意三數乘積的最大值

解題思路

先排序.然後比較 前兩個元素*最後一個元素的乘積 和 最後三個元素的乘積 取最大值

來源

https://app.codility.com/programmers/lessons/6-sorting/max_product_of_three/

解答

https://github.com/kimi0230/LeetcodeGolang/blob/master/Codility/Lesson/0006.Sorting/MaxProductOfThree/MaxProductOfThree.go

package MaxProductOfThree

import "sort"

func max(a, b int) int {
    if a > b {
        return a
    }
    return b
}

func Solution(A []int) int {
    sort.Ints(A)
    aLen := len(A)
    return max(A[0]*A[1]*A[aLen-1], A[aLen-1]*A[aLen-2]*A[aLen-3])
}