02. Special Subsequence JS Essentials Retake-06 August 2019

function specialSubsequence(input) {
    let currentSpecialSubSequence = [];
    let maxSpecialSubsequence = [];
    let isPreviosePositiveNumber = false;
    let isPreviouseNegativeNumber = false;
    let i = 0;

    while (i < input.length) {
        if (input[i] > 0) {
            isPreviosePositiveNumber = true;
            currentSpecialSubSequence.push(input[i]);
            break;
        } else if (input[i] < 0) {
            isPreviouseNegativeNumber = true;
            currentSpecialSubSequence.push(input[i]);
            break;
        }
        i++;
    }

    for (index = i + 1; index < input.length; index++) {
        if (isPreviosePositiveNumber && input[index] < 0) {
            isPreviosePositiveNumber = false;
            isPreviouseNegativeNumber = true;
            currentSpecialSubSequence.push(input[index]);
            if (maxSpecialSubsequence.length < currentSpecialSubSequence.length) {
                maxSpecialSubsequence = [];
                maxSpecialSubsequence = currentSpecialSubSequence.slice(0);
            }
        } else if (isPreviouseNegativeNumber && input[index] > 0) {
            isPreviosePositiveNumber = true;
            isPreviouseNegativeNumber = false;
            currentSpecialSubSequence.push(input[index]);
            if (maxSpecialSubsequence.length < currentSpecialSubSequence.length) {
                maxSpecialSubsequence = [];
                maxSpecialSubsequence = currentSpecialSubSequence.slice(0);
            }
        } else {
            currentSpecialSubSequence = [];
            while (input[index] === 0) {
                index++;
            }
            if (input[index] > 0) {
                isPreviosePositiveNumber = true;
                isPreviouseNegativeNumber = false;
                currentSpecialSubSequence.push(input[index]);
            } else {
                isPreviouseNegativeNumber = true;
                isPreviosePositiveNumber = false;
                currentSpecialSubSequence.push(input[index]);
            }
        }
    }

    console.log(maxSpecialSubsequence.length > 0
        ? `The longest sequence is ${maxSpecialSubsequence.join(', ')}`
        : `In ${input.join(', ')} no special sequence is found`)
}

specialSubsequence([0, 1, -2, 1, -1, 2, 0, 0]);
specialSubsequence([-1, -1, -1, 1, -1])
specialSubsequence([1, 2, 3, 4, 5]);
// The result is:
// The longest sequence is 1, -2, 1, -1, 2
// The longest sequence is -1, 1, -1
// In 1, 2, 3, 4, 5 no special sequence is found