1502. Can Make Arithmetic Progression From Sequence.md

1502. Can Make Arithmetic Progression From Sequence

Difficuly : Easy

Related Topic : Array、Sort

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the first one in Weekly Contest 196.

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

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
• -10^6 <= arr[i] <= 10^6

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Solution

• mine
  • Java
    • Arrays.sort Runtime: 1 ms, faster than 99.73%, Memory Usage: 38.8 MB, less than 100.00% of Java online submissions

      // O(N * logN)time
      // O(N)space
      public boolean canMakeArithmeticProgression(int[] arr) {
          Arrays.sort(arr);
          int d = arr[1] - arr[0];
          for(int i = 2; i < arr.length; i++){
              if(arr[i] - arr[i - 1] != d){
                  return false;
              }
          }
          return true;
      }
      

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