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LeetCode-80-Remove-Duplicates-from-Sorted-Array-II.java
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LeetCode-80-Remove-Duplicates-from-Sorted-Array-II.java
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/*
LeetCode: https://leetcode.com/problems/remove-duplicates-from-sorted-array-ii/
LintCode: http://www.lintcode.com/problem/remove-duplicates-from-sorted-array-ii/
JiuZhang: http://www.jiuzhang.com/solutions/remove-duplicates-from-sorted-array-ii/
ProgramCreek: http://www.programcreek.com/2013/01/leetcode-remove-duplicates-from-sorted-array-ii-java/
Analysis:
Scan from 3rd element. Just to see each curr ele and prev -1, prev
*/
public class Solution {
// 1. Two Pointers
public int removeDuplicates(int[] nums) {
if(nums == null) return 0;
if(nums.length <= 2) return nums.length;
int prev = 1, curr = 2; //scan from the third element (curr)
while(curr < nums.length){
if(nums[prev - 1] == nums[curr] && nums[prev] == nums[curr]){
curr++;
continue;
}
prev++;
nums[prev] = nums[curr];
curr++;
}
return prev + 1;
}
// 2. One Pointer
/*
https://leetcode.com/problems/remove-duplicates-from-sorted-array-ii/discuss/27976/3-6-easy-lines-C%2B%2B-Java-Python-Ruby
https://leetcode.com/problems/remove-duplicates-from-sorted-array-ii/discuss/27987/Short-and-Simple-Java-solution-(easy-to-understand)
Smart and fast. This could also apply to LeetCode-26-Remove-Duplicates-from-Sorted-Array.java
*/
public int removeDuplicates(int[] nums) {
if (nums.length <= 2) return nums.length;
int curr = 0; // the index of leftest duplicate element.
for (int num : nums) {
if (curr < 2 || num > nums[curr - 2]) {
// find a non-duplicate num
nums[curr++] = num;
}
}
return curr;
}
}