Follow up for "remove duplicates ":
What if duplicates are allowed at mostTwice?
For example,
Given sorted array A =[1,1,1,2,2,3]
,
Your function shocould return length =5
, And a is now[1,1,2,2,3]
.
Https://oj.leetcode.com/problems/remove-duplicates-from-sorted-array-ii/
Idea: Double pointer method. However, this is the comparison of the previous element.
public class Solution { public int removeDuplicates(int[] A) { int n = A.length; if (n <= 2) return n; int index = 2; for (int i = 2; i < n; i++) { if (A[i] != A[index - 2]) A[index++] = A[i]; } return index; } public int removeDuplicates2(int[] A) { if (A.length <= 2) return A.length; int prev = 1; // point to previous int curr = 2; // point to current while (curr < A.length) { if (A[curr] == A[prev] && A[curr] == A[prev - 1]) { curr++; } else { prev++; A[prev] = A[curr]; curr++; } } return prev + 1; } public static void main(String[] args) { System.out.println(new Solution().removeDuplicates(new int[] { 1, 1, 1, 2 })); System.out.println(new Solution().removeDuplicates(new int[] { 1, 1, 2, 2, 2, 2, 3, 3, 3, 4, 4, 5, 5 })); System.out.println(new Solution().removeDuplicates(new int[] {})); System.out.println(new Solution().removeDuplicates(new int[] { 1 })); System.out.println(new Solution().removeDuplicates(new int[] { 1, 1 })); }}
View code
Refer:
Http://www.programcreek.com/2013/01/leetcode-remove-duplicates-from-sorted-array-ii-java/
Http://zhangxc.com/2013/11/leetcode-remove-duplicates-from-sorted-array-2