What is the time complexity of Mergesort algorithm?
1) Best: O(nlogn), Worst: O(nlogn), Space: O(n)
2) Best: O(nlogn), Worst: O(n²), Space: O(n)
3) Best: O(n), Worst: O(n²), Space: O(n)
4) Best: O(nlogn), Worst: O(nlogn), Space: O(1)