#93 · #75 · Sort Colors(颜色分类)

Given an array nums with n objects coloured red (0), white (1) or blue (2), sort them in place so that objects of the same colour are adjacent, in the order red, white, blue. You must solve it without using the library sort function, ideally in a single pass. Constraints: 1 <= n <= 300, nums[i] is 0, 1 or 2.