1630-ArithmeticSubarrays.go

package main

// 1630. Arithmetic Subarrays
// A sequence of numbers is called arithmetic if it consists of at least two elements, 
// and the difference between every two consecutive elements is the same. 
// More formally, a sequence s is arithmetic if and only if s[i+1] - s[i] == s[1] - s[0] for all valid i.

// For example, these are arithmetic sequences:
//     1, 3, 5, 7, 9
//     7, 7, 7, 7
//     3, -1, -5, -9

// The following sequence is not arithmetic:
//     1, 1, 2, 5, 7

// You are given an array of n integers, nums, 
// and two arrays of m integers each, l and r, representing the m range queries, 
// where the ith query is the range [l[i], r[i]]. All the arrays are 0-indexed.

// Return a list of boolean elements answer, 
// where answer[i] is true if the subarray nums[l[i]], nums[l[i]+1], ... , nums[r[i]] can be rearranged to form an arithmetic sequence, and false otherwise.

// Example 1:
// Input: nums = [4,6,5,9,3,7], l = [0,0,2], r = [2,3,5]
// Output: [true,false,true]
// Explanation:
// In the 0th query, the subarray is [4,6,5]. This can be rearranged as [6,5,4], which is an arithmetic sequence.
// In the 1st query, the subarray is [4,6,5,9]. This cannot be rearranged as an arithmetic sequence.
// In the 2nd query, the subarray is [5,9,3,7]. This can be rearranged as [3,5,7,9], which is an arithmetic sequence.

// Example 2:
// Input: nums = [-12,-9,-3,-12,-6,15,20,-25,-20,-15,-10], l = [0,1,6,4,8,7], r = [4,4,9,7,9,10]
// Output: [false,true,false,false,true,true]

// Constraints:
//     n == nums.length
//     m == l.length
//     m == r.length
//     2 <= n <= 500
//     1 <= m <= 500
//     0 <= l[i] < r[i] < n
//     -10^5 <= nums[i] <= 10^5

import "fmt"
import "sort"

func checkArithmeticSubarrays(nums []int, l []int, r []int) []bool {
    n := len(l)
    res := make([]bool, n)
    for i := 0; i < n; i++ {
        arr := make([]int, r[i] - l[i] + 1)
        copy(arr, nums[l[i]:r[i] + 1])
        sort.Ints(arr)
        diff, flag := arr[1] - arr[0], true
        for j := 2; j < len(arr); j++ {
            if arr[j] - arr[j - 1] != diff {
                flag = false
                break
            }
        }
        res[i] = flag
    }
    return res
}

func main() {
    // Example 1:
    // Input: nums = [4,6,5,9,3,7], l = [0,0,2], r = [2,3,5]
    // Output: [true,false,true]
    // Explanation:
    // In the 0th query, the subarray is [4,6,5]. This can be rearranged as [6,5,4], which is an arithmetic sequence.
    // In the 1st query, the subarray is [4,6,5,9]. This cannot be rearranged as an arithmetic sequence.
    // In the 2nd query, the subarray is [5,9,3,7]. This can be rearranged as [3,5,7,9], which is an arithmetic sequence.
    fmt.Println(checkArithmeticSubarrays([]int{4,6,5,9,3,7}, []int{0,0,2}, []int{2,3,5})) // [true,false,true]
    // Example 2:
    // Input: nums = [-12,-9,-3,-12,-6,15,20,-25,-20,-15,-10], l = [0,1,6,4,8,7], r = [4,4,9,7,9,10]
    // Output: [false,true,false,false,true,true]
    fmt.Println(checkArithmeticSubarrays([]int{-12,-9,-3,-12,-6,15,20,-25,-20,-15,-10}, []int{0,1,6,4,8,7}, []int{4,4,9,7,9,10})) // [false,true,false,false,true,true]
}