/**

***This is method just needs one int ,and needn't any other value

***The main core is the i is much fast increasing than num, so I save the value in nums [num-1].

**/

public class Solution {

public int removeDuplicates(int[] nums) {

int num=1,len=nums.length;

if(len==0||len==1)

{

return len;

}

for(int i=1;i<nums.length;i++)

{

if(nums[num-1]!=nums[i]) //if not the same,just save the different number in the original nums array

{

num++;

nums[num-1]=nums[i];

}

}

return num;

```
}
```

}