2422-MergeOperationsToTurnArrayIntoAPalindrome.go

package main

// 2422. Merge Operations to Turn Array Into a Palindrome
// You are given an array nums consisting of positive integers.

// You can perform the following operation on the array any number of times:
//     Choose any two adjacent elements and replace them with their sum.
//         For example, if nums = [1,2,3,1], you can apply one operation to make it [1,5,1].

// Return the minimum number of operations needed to turn the array into a palindrome.

// Example 1:
// Input: nums = [4,3,2,1,2,3,1]
// Output: 2
// Explanation: We can turn the array into a palindrome in 2 operations as follows:
// - Apply the operation on the fourth and fifth element of the array, nums becomes equal to [4,3,2,3,3,1].
// - Apply the operation on the fifth and sixth element of the array, nums becomes equal to [4,3,2,3,4].
// The array [4,3,2,3,4] is a palindrome.
// It can be shown that 2 is the minimum number of operations needed.

// Example 2:
// Input: nums = [1,2,3,4]
// Output: 3
// Explanation: We do the operation 3 times in any position, we obtain the array [10] at the end which is a palindrome.

// Constraints:
//     1 <= nums.length <= 10^5
//     1 <= nums[i] <= 10^6

import "fmt"

func minimumOperations(nums []int) int {
    res, j := 0, len(nums) - 1
    for i := 0; i < j;  {
        if nums[i] == nums[j] {
            j--
            i++
            continue
        } else if nums[i] < nums[j] {
            nums[i + 1] += nums[i]
            i++
        } else {
            nums[j - 1] += nums[j]
            j--
        }
        res++
    }
    return res
}

func main() {
    // Example 1:
    // Input: nums = [4,3,2,1,2,3,1]
    // Output: 2
    // Explanation: We can turn the array into a palindrome in 2 operations as follows:
    // - Apply the operation on the fourth and fifth element of the array, nums becomes equal to [4,3,2,3,3,1].
    // - Apply the operation on the fifth and sixth element of the array, nums becomes equal to [4,3,2,3,4].
    // The array [4,3,2,3,4] is a palindrome.
    // It can be shown that 2 is the minimum number of operations needed.
    fmt.Println(minimumOperations([]int{4,3,2,1,2,3,1})) // 2
    // Example 2:
    // Input: nums = [1,2,3,4]
    // Output: 3
    // Explanation: We do the operation 3 times in any position, we obtain the array [10] at the end which is a palindrome.
    fmt.Println(minimumOperations([]int{1,2,3,4})) // 3
}