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26. remove duplicates from sorted array

admin 11月 13, 2020 0

Question

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.

Analysis

Use two pointer:

record current index postion
iterate array and compare element with cur postion if the value is different replace the nums[cur++] = nums[fast]

Complexity

Time Complexity: O(n)

Solution

public int (int[] nums) {
    if (nums.length < 2) return nums.length;
    int cur = 1;
    for (int fast = 1; fast < nums.length; ++fast) {
        if (nums[fast] != nums[fast-1]){
          nums[cur++] = nums[fast];  
        } 
    }
    return cur;
}