0026. Remove Duplicates from Sorted Array.js

// 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]);
// }


// 双指针
/**
 * @param {number[]} nums
 * @return {number}
 */
var removeDuplicates = function(nums) {
  let i = 0
  let j = 0
  while (j < nums.length) {
    if (nums[j] !== nums[i]) {
      i++
      nums[i] = nums[j]
    }
    j++
  }
  return i + 1
};
// Runtime: 72 ms, faster than 70.82% of JavaScript online submissions for Remove Duplicates from Sorted Array.
// Memory Usage: 36.7 MB, less than 100.00% of JavaScript online submissions for Remove Duplicates from Sorted Array.