leetcode

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1464. Maximum Product of Two Elements in an Array

题目

Given the array of integers nums, you will choose two different indices i and j of that array. Return the maximum value of (nums[i]-1)*(nums[j]-1).

Example 1:

Input: nums = [3,4,5,2]
Output: 12 
Explanation: If you choose the indices i=1 and j=2 (indexed from 0), you will get the maximum value, that is, (nums[1]-1)*(nums[2]-1) = (4-1)*(5-1) = 3*4 = 12. 

Example 2:

Input: nums = [1,5,4,5]
Output: 16
Explanation: Choosing the indices i=1 and j=3 (indexed from 0), you will get the maximum value of (5-1)*(5-1) = 16.

Example 3:

Input: nums = [3,7]
Output: 12

Constraints:

• 2 <= nums.length <= 500
• 1 <= nums[i] <= 10^3

题目大意

给你一个整数数组 nums，请你选择数组的两个不同下标 i 和 j，使 (nums[i]-1)*(nums[j]-1) 取得最大值。请你计算并返回该式的最大值。

解题思路

• 简单题。循环一次，按照题意动态维护 2 个最大值，从而也使得 (nums[i]-1)*(nums[j]-1) 能取到最大值。

代码

package leetcode

func maxProduct(nums []int) int {
	max1, max2 := 0, 0
	for _, num := range nums {
		if num >= max1 {
			max2 = max1
			max1 = num
		} else if num <= max1 && num >= max2 {
			max2 = num
		}
	}
	return (max1 - 1) * (max2 - 1)
}