README_EN.md

1502. Can Make Arithmetic Progression From Sequence

中文文档

Description

A sequence of numbers is called an arithmetic progression if the difference between any two consecutive elements is the same.

Given an array of numbers arr, return true if the array can be rearranged to form an arithmetic progression. Otherwise, return false.

 

Example 1:

Input: arr = [3,5,1]
Output: true
Explanation: We can reorder the elements as [1,3,5] or [5,3,1] with differences 2 and -2 respectively, between each consecutive elements.

Example 2:

Input: arr = [1,2,4]
Output: false
Explanation: There is no way to reorder the elements to obtain an arithmetic progression.

 

Constraints:

• 2 <= arr.length <= 1000
• -106 <= arr[i] <= 106

Solutions

Python3

class Solution:
    def canMakeArithmeticProgression(self, arr: List[int]) -> bool:
        arr.sort()
        for i in range(1, len(arr) - 1):
            if (arr[i] << 1) != arr[i - 1] + arr[i + 1]:
                return False
        return True

Java

class Solution {
    public boolean canMakeArithmeticProgression(int[] arr) {
        Arrays.sort(arr);
        for (int i = 1; i < arr.length - 1; ++i) {
            if ((arr[i] << 1) != arr[i - 1] + arr[i + 1]) {
                return false;
            }
        }
        return true;
    }
}

JavaScript

/**
 * @param {number[]} arr
 * @return {boolean}
 */
var canMakeArithmeticProgression = function (arr) {
    arr.sort((a, b) => a - b);
    for (let i = 1; i < arr.length - 1; i++) {
        if (arr[i] << 1 != arr[i - 1] + arr[i + 1]) return false;
    }
    return true;
};

TypeScript

function canMakeArithmeticProgression(arr: number[]): boolean {
    arr.sort((a, b) => a - b);
    const n = arr.length;
    for (let i = 2; i < n; i++) {
        if (arr[i - 2] - arr[i - 1] !== arr[i - 1] - arr[i]) {
            return false;
        }
    }
    return true;
}

function canMakeArithmeticProgression(arr: number[]): boolean {
    const n = arr.length;
    const map = new Map<number, number>();
    let min = Infinity;
    let max = -Infinity;
    for (const num of arr) {
        map.set(num, (map.get(num) ?? 0) + 1);
        min = Math.min(min, num);
        max = Math.max(max, num);
    }
    if (max === min) {
        return true;
    }
    if ((max - min) % (arr.length - 1)) {
        return false;
    }
    const diff = (max - min) / (arr.length - 1);
    for (let i = min; i <= max; i += diff) {
        if (map.get(i) !== 1) {
            return false;
        }
    }
    return true;
}

Rust

impl Solution {
    pub fn can_make_arithmetic_progression(mut arr: Vec<i32>) -> bool {
        arr.sort();
        let n = arr.len();
        for i in 2..n {
            if arr[i - 2] - arr[i - 1] != arr[i - 1] - arr[i] {
                return false;
            }
        }
        true
    }
}

use std::collections::HashMap;
impl Solution {
    pub fn can_make_arithmetic_progression(arr: Vec<i32>) -> bool {
        let n = arr.len() as i32;
        let mut min = i32::MAX;
        let mut max = i32::MIN;
        let mut map = HashMap::new();
        for &num in arr.iter() {
            *map.entry(num).or_insert(0) += 1;
            min = min.min(num);
            max = max.max(num);
        }
        if min == max {
            return true;
        }
        if (max - min) % (n - 1) != 0 {
            return false;
        }
        let diff = (max - min) / (n - 1);
        let mut k = min;
        while k <= max {
            if *map.get(&k).unwrap_or(&0) != 1 {
                return false;
            }
            k += diff;
        }
        true
    }
}

C

int cmp(const void *a, const void *b) {
    return *(int *) a - *(int *) b;
}

bool canMakeArithmeticProgression(int *arr, int arrSize) {
    qsort(arr, arrSize, sizeof(int), cmp);
    for (int i = 2; i < arrSize; i++) {
        if (arr[i - 2] - arr[i - 1] != arr[i - 1] - arr[i]) {
            return 0;
        }
    }
    return 1;
}

...