2784. Check if Array is Good

/**
 * Problem: LeetCode 2784 - Check if Array is Good
 * Difficulty: Easy
 * Language: Java
 * Author: CodeByTushu
 */
class Solution {
    public boolean isGood(int[] nums) {
        int n = nums.length - 1;
        if (n < 1) {
            return false;
        }

        int[] count = new int[n + 1];
        for (int num : nums) {
            if (num < 1 || num > n) {
                return false;
            }
            count[num]++;
        }

        // Each number from 1 to n - 1 must appear exactly once
        for (int i = 1; i < n; i++) {
            if (count[i] != 1) {
                return false;
            }
        }

        // The number n must appear exactly twice
        return count[n] == 2;
    }
}

"""
Problem: LeetCode 2784 - Check if Array is Good
Difficulty: Easy
Language: Python
Author: CodeByTushu
"""
from typing import List

class Solution:
    def isGood(self, nums: List[int]) -> bool:
        n = len(nums) - 1
        if n < 1:
            return False

        count = [0] * (n + 1)
        for num in nums:
            if num < 1 or num > n:
                return False
            count[num] += 1

        # Each number from 1 to n - 1 must appear exactly once
        for i in range(1, n):
            if count[i] != 1:
                return False

        # The number n must appear exactly twice
        return count[n] == 2

/**
 * Problem: LeetCode 2784 - Check if Array is Good
 * Difficulty: Easy
 * Language: C++
 * Author: CodeByTushu
 */
#include <vector>

using namespace std;

class Solution {
public:
    bool isGood(vector<int>& nums) {
        int n = nums.size() - 1;
        if (n < 1) {
            return false;
        }

        vector<int> count(n + 1, 0);
        for (int num : nums) {
            if (num < 1 || num > n) {
                return false;
            }
            count[num]++;
        }

        // Each number from 1 to n - 1 must appear exactly once
        for (int i = 1; i < n; i++) {
            if (count[i] != 1) {
                return false;
            }
        }

        // The number n must appear exactly twice
        return count[n] == 2;
    }
};

/**
 * Problem: LeetCode 2784 - Check if Array is Good
 * Difficulty: Easy
 * Language: JavaScript
 * Author: CodeByTushu
 */
var isGood = function(nums) {
    const n = nums.length - 1;
    if (n < 1) {
        return false;
    }

    const count = new Int32Array(n + 1);
    for (const num of nums) {
        if (num < 1 || num > n) {
            return false;
        }
        count[num]++;
    }

    // Each number from 1 to n - 1 must appear exactly once
    for (let i = 1; i < n; i++) {
        if (count[i] !== 1) {
            return false;
        }
    }

    // The number n must appear exactly twice
    return count[n] === 2;
};