# Remove Duplicate Numbers in Array

ID: 521; easy

## Solution 1 (Java)

``````public class Solution {
/**
* @param nums: an array of integers
* @return: the number of unique integers
*/
public int deduplication(int[] nums) {
Map<Integer, Boolean> map = new HashMap<>();
for (int num : nums) {
map.putIfAbsent(num, true);
}
int res = 0;
for (int key : map.keySet()) {
nums[res++] = key;
}
return res;
}
}``````

### Notes

• Time complexity: `O(n)`

• Space complexity: `O(n)`

## Solution 2 (Java)

``````public class Solution {
/**
* @param nums: an array of integers
* @return: the number of unique integers
*/
public int deduplication(int[] nums) {
if (nums == null || nums.length == 0)
return 0;
Arrays.sort(nums);
int len = 0;
for (int i = 0; i < nums.length; i++) {
if (nums[i] != nums[len]) {
nums[++len] = nums[i];
}
}
return len + 1;
}
}
//                    i
// [1,2,3,4,5,6,3,4,5,6]
//            l``````

### Notes

• Time complexity: `O(nlogn)` from sorting

• Space complexity: `O(n)`

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