2460-ApplyOperationsToAnArray.go

package main

// 2460. Apply Operations to an Array
// You are given a 0-indexed array nums of size n consisting of non-negative integers.

// You need to apply n - 1 operations to this array where, in the ith operation (0-indexed), 
// you will apply the following on the ith element of nums:
//     If nums[i] == nums[i + 1], then multiply nums[i] by 2 and set nums[i + 1] to 0. 
//     Otherwise, you skip this operation.

// After performing all the operations, shift all the 0's to the end of the array.
//     For example, the array [1,0,2,0,0,1] after shifting all its 0's to the end, is [1,2,1,0,0,0].

// Return the resulting array.

// Note that the operations are applied sequentially, not all at once.

// Example 1:
// Input: nums = [1,2,2,1,1,0]
// Output: [1,4,2,0,0,0]
// Explanation: We do the following operations:
// - i = 0: nums[0] and nums[1] are not equal, so we skip this operation.
// - i = 1: nums[1] and nums[2] are equal, we multiply nums[1] by 2 and change nums[2] to 0. The array becomes [1,4,0,1,1,0].
// - i = 2: nums[2] and nums[3] are not equal, so we skip this operation.
// - i = 3: nums[3] and nums[4] are equal, we multiply nums[3] by 2 and change nums[4] to 0. The array becomes [1,4,0,2,0,0].
// - i = 4: nums[4] and nums[5] are equal, we multiply nums[4] by 2 and change nums[5] to 0. The array becomes [1,4,0,2,0,0].
// After that, we shift the 0's to the end, which gives the array [1,4,2,0,0,0].

// Example 2:
// Input: nums = [0,1]
// Output: [1,0]
// Explanation: No operation can be applied, we just shift the 0 to the end.

// Constraints:
//     2 <= nums.length <= 2000
//     0 <= nums[i] <= 1000

import "fmt"

func applyOperations(nums []int) []int {
    res, n := []int{}, len(nums)
    for i := 1; i < n; i++ {
        if nums[i] == nums[i-1] {
            nums[i - 1],  nums[i] = 2 * nums[i - 1], 0
        }
    }
    for _, v := range nums {
        if v != 0 { res = append(res, v) }
    }
    for _, v := range nums {
        if v == 0 { res = append(res, v) }
    }
    return res
}

func applyOperations1(nums []int) []int {
    j, n := 0, len(nums)
    for i := 0; i < n; i++ {
        if i + 1 < n && nums[i] == nums[i+1] {
            nums[i], nums[i + 1] = 2 * nums[i], 0
        }
        if nums[i] != 0 {
            nums[i], nums[j] = nums[j], nums[i]
            j++
        }
    }
    return nums
}

func main() {
    // Example 1:
    // Input: nums = [1,2,2,1,1,0]
    // Output: [1,4,2,0,0,0]
    // Explanation: We do the following operations:
    // - i = 0: nums[0] and nums[1] are not equal, so we skip this operation.
    // - i = 1: nums[1] and nums[2] are equal, we multiply nums[1] by 2 and change nums[2] to 0. The array becomes [1,4,0,1,1,0].
    // - i = 2: nums[2] and nums[3] are not equal, so we skip this operation.
    // - i = 3: nums[3] and nums[4] are equal, we multiply nums[3] by 2 and change nums[4] to 0. The array becomes [1,4,0,2,0,0].
    // - i = 4: nums[4] and nums[5] are equal, we multiply nums[4] by 2 and change nums[5] to 0. The array becomes [1,4,0,2,0,0].
    // After that, we shift the 0's to the end, which gives the array [1,4,2,0,0,0].
    fmt.Println(applyOperations([]int{1,2,2,1,1,0})) // [1,4,2,0,0,0]
    // Example 2:
    // Input: nums = [0,1]
    // Output: [1,0]
    // Explanation: No operation can be applied, we just shift the 0 to the end.
    fmt.Println(applyOperations([]int{0,1})) // [1,0]

    fmt.Println(applyOperations1([]int{1,2,2,1,1,0})) // [1,4,2,0,0,0]
    fmt.Println(applyOperations1([]int{0,1})) // [1,0]
}