2321.go

// Source: https://leetcode.com/problems/maximum-score-of-spliced-array
// Title: Maximum Score Of Spliced Array
// Difficulty: Hard
// Author: Mu Yang <http://muyang.pro>

////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
// You are given two 0-indexed integer arrays nums1 and nums2, both of length n.
// You can choose two integers left and right where 0 <= left <= right < n and swap the subarray nums1[left...right] with the subarray nums2[left...right].
//   * For example, if nums1 = [1,2,3,4,5] and nums2 = [11,12,13,14,15] and you choose left = 1 and right = 2, nums1 becomes [1,12,13,4,5] and nums2 becomes [11,2,3,14,15].
// You may choose to apply the mentioned operation once or not do anything.
// The score of the arrays is the maximum of sum(nums1) and sum(nums2), where sum(arr) is the sum of all the elements in the array arr.
// Return the maximum possible score.
//
// A subarray is a contiguous sequence of elements within an array. arr[left...right] denotes the subarray that contains the elements of nums between indices left and right (inclusive).
//
// Example 1:
//
//   Input: nums1 = [60,60,60], nums2 = [10,90,10]
//   Output: 210
//   Explanation:
//     Choosing left = 1 and right = 1, we have nums1 = [60,90,60] and nums2 = [10,60,10].
//     The score is max(sum(nums1), sum(nums2)) = max(210, 80) = 210.
//
// Example 2:
//
//   Input: nums1 = [20,40,20,70,30], nums2 = [50,20,50,40,20]
//   Output: 220
//   Explanation:
//     Choosing left = 3, right = 4, we have nums1 = [20,40,20,40,20] and nums2 = [50,20,50,70,30].
//     The score is max(sum(nums1), sum(nums2)) = max(140, 220) = 220.
//
// Example 3:
//
//   Input: nums1 = [7,11,13], nums2 = [1,1,1]
//   Output: 31
//   Explanation:
//     We choose not to swap any subarray.
//     The score is max(sum(nums1), sum(nums2)) = max(31, 3) = 31.
//
// Constraints:
//
//   n == nums1.length == nums2.length
//   1 <= n <= 10^5
//   1 <= nums1[i], nums2[i] <= 10^4
//
////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////

package main

func maximumsSplicedArray(nums1 []int, nums2 []int) int {
	n := len(nums1)

	sum1 := 0
	sum2 := 0
	for i := 0; i < n; i++ {
		sum1 += nums1[i]
		sum2 += nums2[i]
	}

	// Get max sub array
	maxGlobal := 0
	maxEndHere := maxGlobal
	minGlobal := 0
	minEndHere := minGlobal

	for i := 0; i < n; i++ {
		num := nums2[i] - nums1[i]
		maxEndHere = _max(maxEndHere+num, num)
		maxGlobal = _max(maxGlobal, maxEndHere)

		minEndHere = _min(minEndHere+num, num)
		minGlobal = _min(minGlobal, minEndHere)
	}

	return _max(sum1+maxGlobal, sum2-minGlobal)
}

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

func _min(a, b int) int {
	if a < b {
		return a
	}
	return b
}