Given an array of integers A, a move consists of choosing any `A[i]`, and incrementing it by `1`.

Return the least number of moves to make every value in `A` unique.

Example 1:

```Input: [1,2,2]
Output: 1
Explanation:  After 1 move, the array could be [1, 2, 3].
```

Example 2:

```Input: [3,2,1,2,1,7]
Output: 6
Explanation:  After 6 moves, the array could be [3, 4, 1, 2, 5, 7].
It can be shown with 5 or less moves that it is impossible for the array to have all unique values.
```

Note:

1. `0 <= A.length <= 40000`
2. `0 <= A[i] < 40000`

Solution:

``````/**
* @param {number[]} A
* @return {number}
*/
var minIncrementForUnique = function(A) {
// sort array first!
A.sort((a, b) => a - b);
let ans = 0;
for (let i = 1; i < A.length; i++) {
// skip if A[i] > A[i - 1], no need to change
if (A[i] > A[i - 1]) continue;
// when A[i] >= A[i - 1] after previous modification
// record how many move to make them unique
ans += (A[i - 1] - A[i]) + 1;
// make A[i] slightly bigger than A[i - 1]
A[i] = A[i - 1] + 1;
}
return ans;
};``````