Sort Colors

Sort 3 colors using two pointers.

Sort Colors II

Rainbow Sort

Copy List with Random Pointer

One LinkedList O(1) space problem -- improved from O(n) space using hasing.

Subarray Sum Closest

PrefixSum that works on this subarray sum problem.

Maximum Subarray

PrefixSum that fits all subarray sum problem.

Subarray Sum

PrefixSum that fits all subarray sum problem.

Triangle

The other 4 sides of one classic DP problem (solve the DP problem in 5 days).

3Sum

Three Sum problem, well I confess it is actually a Two Sum problem...

Two Sum - Unique pairs

Two Sum problem

Find Minimum in Rotated Sorted Array II

Binary Search problems