2784. Check if Array is Good

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 - 1exactly once, plus two occurrences of n). For example, base[1] = [1, 1] andbase[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.

class Solution {
public:
    bool isGood(vector<int>& nums) {
        sort(begin(nums), end(nums));
        if(nums.size() == 1) return false;
        for(int i = 0; i < nums.size() - 1; i++) {
            if(nums[i] != i + 1) return false;
        }
        if(nums.back() != nums[nums.size() - 2]) return false;
        return true;
    }
};