Force deduction method summary: double pointer

Some of the contents of this article refer to

https://labuladong.github.io/algo/2/18/21/

There are two main types of double pointer techniques ： Left and right pointers and fast and slow pointers .

The so-called left and right pointers , That is, two pointers go opposite or opposite ; And the so-called fast and slow pointer , Is that the two pointers go in the same direction , Fast and slow .

26. Remove duplicate items from an ordered array Easy Double pointer - Speed pointer 2022/5/18

To give you one Ascending order Array of nums , Would you please In situ Delete duplicate elements , Make each element Only once , Returns the new length of the deleted array . Elemental Relative order It should be maintained Agreement .
Example ：
Input ：nums = [1,1,2]
Output ：2, nums = [1,2,_]
explain ： Function should return the new length 2 , And the original array nums The first two elements of are modified to 1, 2 . You don't need to think about the elements in the array that follow the new length .

The fast and slow pointer in the double pointer ： Go ahead and look for the way , If the speed pointer refers to different elements , Slow the pointer back , The fast pointer is assigned a corresponding value to the slow pointer pointing , Move the pointer to the right , If the indicated elements are the same , Then the fast pointer moves directly to the right .

subject 83. Delete duplicates in the sorting linked list