選擇數字 - HakerRank 解決方案 - Javascript

function pickingNumbers(a) {
    // Create an array to store frequency of each element in the input array
    let frequency = new Array(100).fill(0);

    // Count frequency of each element
    for (let i = 0; i < a.length; i++) {
        frequency[a[i]]++;
    }

    // Initialize a variable to store the maximum length of subarray found
    let maxLength = 0;

    // Traverse through frequency array to find the longest subarray
    for (let i = 1; i < frequency.length; i++) {
        // The length of a valid subarray is the sum of the frequency of
        // the current element and the previous element
        maxLength = Math.max(maxLength, frequency[i] + frequency[i - 1]);
    }

    return maxLength;
}