Interview-Tiktok-OA-monotonic

Summary of Thoughts

只看偶数下标上的元素（numbers[0]、numbers[2]、numbers[4]…），判断这串数字是不是单调的。

• 严格递增: 返回 “increasing”
• 严格递减: 返回 “decreasing”
• 既不是递增也不是递减（含相等的情况: 返回 “none”

Code（Java）

String solution(int[] numbers) {
    int[] filtered = new int[(numbers.length + 1) / 2];
    int idx = 0;
    boolean inc = true;
    boolean dec = true;
    for (int i = 0; i < numbers.length; i = i + 2) {
      filtered[idx] = numbers[i];
      idx++;
    }
    for (int i = 0; i < idx - 1; i++) {
      if (filtered[i] <= filtered[i + 1]) dec = false;
      if (filtered[i] >= filtered[i + 1]) inc = false;
    }
    if (inc) return "increasing";
    if (dec) return "decreasing";
    return "none";
}

String solution(int[] numbers) {
    boolean inc = true, dec = true;
    for (int i = 2; i < numbers.length; i += 2) {
        if (numbers[i] <= numbers[i - 2]) inc = false;
        if (numbers[i] >= numbers[i - 2]) dec = false;
    }
    if (inc) return "increasing";
    if (dec) return "decreasing";
    return "none";
}