Package g2701_2800.s2784_check_if_array_is_good

Class Solution

  • public class Solution
extends Object
    2784 - Check if Array is Good.

    Easy

    You are given an integer array nums. We consider an array good if it is a permutation of an array base[n].

    base[n] = [1, 2, ..., n - 1, n, n] (in other words, it is an array of length n + 1 which contains 1 to n - 1 exactly once, plus two occurrences of n). For example, base[1] = [1, 1] and base[3] = [1, 2, 3, 3].

    Return true if the given array is good, otherwise return false.

    Note: A permutation of integers represents an arrangement of these numbers.

    Example 1:

    Input: nums = [2, 1, 3]

    Output: false

    Explanation: Since the maximum element of the array is 3, the only candidate n for which this array could be a permutation of base[n], is n = 3. However, base[3] has four elements but array nums has three. Therefore, it can not be a permutation of base[3] = [1, 2, 3, 3]. So the answer is false.

    Example 2:

    Input: nums = [1, 3, 3, 2]

    Output: true

    Explanation: Since the maximum element of the array is 3, the only candidate n for which this array could be a permutation of base[n], is n = 3. It can be seen that nums is a permutation of base[3] = [1, 2, 3, 3] (by swapping the second and fourth elements in nums, we reach base[3]). Therefore, the answer is true.

    Example 3:

    Input: nums = [1, 1]

    Output: true

    Explanation: Since the maximum element of the array is 1, the only candidate n for which this array could be a permutation of base[n], is n = 1. It can be seen that nums is a permutation of base[1] = [1, 1]. Therefore, the answer is true.

    Example 4:

    Input: nums = [3, 4, 4, 1, 2, 1]

    Output: false

    Explanation: Since the maximum element of the array is 4, the only candidate n for which this array could be a permutation of base[n], is n = 4. However, base[4] has five elements but array nums has six. Therefore, it can not be a permutation of base[4] = [1, 2, 3, 4, 4]. So the answer is false.

    Constraints:

    • 1 <= nums.length <= 100
    • 1 <= num[i] <= 200

    • Constructor Detail

      • Solution

        public Solution()

    • Method Detail

      • isGood

        public boolean isGood​(int[] nums)