RemoveDuplicatedfromSortedArrayII.java

package medium;
/**
 * ClassName: RemoveDuplicatedfromSortedArrayII.java
 * Auther: chenyiAlone
 * Create Time: 2019/4/28 11:13
 * Description: No.81
 * 思路:
 *      当 j > 0 && nums[i] == nums[j] && nums[j] == nums[j - 1] 时，跳过当前元素
 *      则 !(j > 0 && nums[i] == nums[j] && nums[j] == nums[j - 1]) 即可
 *
 *
 *
 *
 * Given a sorted array nums, remove the duplicates in-place such that duplicates appeared at most twice and return the new length.
 *
 * Do not allocate extra space for another array, you must do this by modifying the input array in-place with O(1) extra memory.
 *
 * Example 1:
 *
 * Given nums = [1,1,1,2,2,3],
 *
 * Your function should return length = 5, with the first five elements of nums being 1, 1, 2, 2 and 3 respectively.
 *
 * It doesn't matter what you leave beyond the returned length.
 * Example 2:
 *
 * Given nums = [0,0,1,1,1,1,2,3,3],
 *
 * Your function should return length = 7, with the first seven elements of nums being modified to 0, 0, 1, 1, 2, 3 and 3 respectively.
 *
 * It doesn't matter what values are set beyond the returned length.
 * Clarification:
 *
 * Confused why the returned value is an integer but your answer is an array?
 *
 * Note that the input array is passed in by reference, which means modification to the input array will be known to the caller as well.
 *
 * Internally you can think of this:
 *
 * // nums is passed in by reference. (i.e., without making a copy)
 * int len = removeDuplicates(nums);
 *
 * // any modification to nums in your function would be known by the caller.
 * // using the length returned by your function, it prints the first len elements.
 * for (int i = 0; i < len; i++) {
 *     print(nums[i]);
 * }
 */
public class RemoveDuplicatedfromSortedArrayII {
    public int removeDuplicates(int[] nums) {
        if (nums.length < 2)
            return nums.length;
        int i = 1, j = 0;
        while (i < nums.length) {
            if (!(j > 0 && nums[i] == nums[j] && nums[j] == nums[j - 1])) {
                nums[++j] = nums[i];
            }
            i++;
        }
        return j + 1;
    }
}