作业1

static int findMissingNumber(int start, int end, List<Integer> list) {    int i = start;    for (Integer n : list) {        if (n != i) {            return n - 1;        }        i++;    }    return end;}

作业2

static int findMissingNumber(int start, int end, List<Integer> list) {    for (int i = start; i <= end; i++) {        if (!list.contains(i)) {            return i;        }    }    throw new IllegalArgumentException("list 并未缺失数据！");}