java - 现有1~100共一百个自然数，已随机放入一个有98个元素的数组a[98]。

Question

要用JAVA实现
要求写出一个尽量简单的方案，找出没有被放入数组的那2个数，并在屏幕上打印这2个数。注意：程序不用实现自然数随机放入数组的过程。

Answer 1

Someone gave an algorithm with a time complexity of O(n^2). I will give you an algorithm with a time complexity of O(n):

public void printNum(int[] arr) {
    int[] result = new int[2];
    int[] heap = new int[101];
    for (int i = 0; i < 98; i++) {
        heap[arr[i]] = 1;
    }
    for (int i = 1; i <= 100; i++) {
        if (heap[i] != 1) {
            System.out.println(i);
        }
    }
}

Answer 2

public int[] findNum(int[] arr) {
    int[] result = new int[2];
    var count = 0;
    for (int i = 1; i <= 100; i++) {
      if (count == 2) break;
      if (arr.indexOf(i) == -1) {
        result.push(i);
        count++;
      }
    }
    return result;
}