[Solved] Determine whether array holds an almost increasing sequence

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There is no need to use a nested loop, nor to create new arrays. This can be done in O(n) time:

function almostIncreasingSequence(sequence) {
    var prev = -Infinity,
        beforePrev = -Infinity,
        allowExceptions = true;
    
    for (var curr of sequence) {
        // Is order not maintained?
        if (curr <= prev) {
            // Give up when this is not the first exception
            if (!allowExceptions) return false;
            allowExceptions = false;
            // Decide whether to skip the current or previous value
            if (curr > beforePrev) prev = curr;
        } else { // Normal case: keep track of two preceding values
            beforePrev = prev;
            prev = curr;
        }
    }
    return true;
}

console.log(almostIncreasingSequence([1,5,3,4,8])); // true
console.log(almostIncreasingSequence([1,5,0,6,8])); // true
console.log(almostIncreasingSequence([1,5,0,4,8])); // false

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solved Determine whether array holds an almost increasing sequence