【LeetCode】Dual pointers, fast and slow pointers to solve problems

1. Remove duplicates in ordered array

class Solution {
    public int removeDuplicates(int[] nums) {
        int fast = 1;
        int slow = 1;

        for(;fast<nums.length;fast++) {
            if( nums[fast] !=nums[fast-1] ) {
                nums[slow] = nums[fast];
                slow++;
            }
        }

        return slow;

    }
}

2. Remove elements

class Solution {
    public int removeElement(int[] nums, int val) {
        int len = nums.length;

        int slow = 0;
        int fast = 0;

        for(fast=0;fast<len;fast++) {
            if( nums[fast] !=val ) {
                nums[slow] = nums[fast];
                slow++;
            }
        }
        return slow;
    }
}