Given a sorted array nums, remove the duplicates in-place such that each element appear only once and return the new length.
Do not allocate extra space for another array, you must do this by modifying the input array in-place with O(1) extra memory.
Given a linked list, swap every two adjacent nodes and return its head.
“You may not modify the values in the list’s nodes, only nodes itself may be changed.l”
Find the kth largest element in an unsorted array. Note that it is the kth largest element in the sorted order, not the kth distinct element.