数组去重方法

1.放入set集合
2.双指针去重

class Solution1 {
    public int removeDuplicates2(int[] nums) {
        Set<Integer> set = new TreeSet();
        for (int i = 0; i < nums.length; i++) {
            set.add(nums[i]);
        }
        int index = 0;
        for (Integer res : set) {
            nums[index] = res;
            index++;
        }
        System.out.println(set);
        return index;
    }

    public int removeDuplicates3(int[] nums) {
        int length = nums.length;
        if (length == 0) {
            return 0;
        }
        int flag1 = 1, flag2 = 1;
        while (flag1 < length) {
            if (nums[flag1] != nums[flag1 - 1]) {
                nums[flag2]=nums[flag1];
                flag2++;
            }
            flag1++;
        }
        return flag2;
    }
}