# [LeetCode] 26. Remove Duplicates from Sorted Array 有序数组中去除重复项

Given a sorted array nums, remove the duplicates in-place such that each element appear only once 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 = [1,1,2],

Your function should return length = 2, with the first two elements of nums being 1 and 2 respectively.

It doesn't matter what you leave beyond the returned length.

Example 2:

Given nums = [0,0,1,1,1,2,2,3,3,4],

Your function should return length = 5, with the first five elements of nums being modified to 0, 1, 2, 3, and 4 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]);
}

class Solution {
public:
int removeDuplicates(vector<int>& nums) {
int pre = 0, cur = 0, n = nums.size();
while (cur < n) {
if (nums[pre] == nums[cur]) ++cur;
else nums[++pre] = nums[cur++];
}
return nums.empty() ? 0 : (pre + 1);
}
};

class Solution {
public:
int removeDuplicates(vector<int>& nums) {
int j = 0, n = nums.size();
for (int i = 0; i < n; ++i) {
if (nums[i] != nums[j]) nums[++j] = nums[i];
}
return nums.empty() ? 0 : (j + 1);
}
};

class Solution {
public:
int removeDuplicates(vector<int>& nums) {
int i = 0;
for (int num : nums) {
if (i < 1 || num > nums[i - 1]) {
nums[i++] = num;
}
}
return i;
}
};

Github 同步地址：

https://github.com/grandyang/leetcode/issues/26

Remove Duplicates from Sorted List

Remove Duplicates from Sorted List II

Remove Duplicates from Sorted Array II

Remove Element

https://leetcode.com/problems/remove-duplicates-from-sorted-array/

https://leetcode.com/problems/remove-duplicates-from-sorted-array/discuss/11757/My-Solution-%3A-Time-O(n)-Space-O(1)

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posted @ 2015-03-11 10:22  Grandyang  阅读(20849)  评论(16编辑  收藏  举报