/**
* @param {number[]} nums
* @return {number}
*/
var removeDuplicates = function (nums) {
if (!nums || nums.length <= 1) return nums.length
let slow = 0,
fast = 1
while (j < nums.length) {
if (nums[slow] !== nums[fast]) {
if (fast - slow > 1) {
nums[slow + 1] = nums[fast]
}
slow++
}
fast++
}
// 返回长度,所以是下标加一
return slow + 1
};