第75題，題目如下:
Given an array nums with n objects colored red, white, or blue, sort them in-place so that objects of the same color are adjacent, with the colors in the order red, white, and blue.
We will use the integers 0, 1, and 2 to represent the color red, white, and blue, respectively.
You must solve this problem without using the library’s sort function.
Example 1:
Input: nums = [2,0,2,1,1,0] Output: [0,0,1,1,2,2]
Example 2:
Input: nums = [2,0,1] Output: [0,1,2]
Constraints:
n == nums.length1 <= n <= 300nums[i]is either0,1, or2.
Follow up: Could you come up with a one-pass algorithm using only constant extra space?
確保在最末尾寫要標記的數字（如果是找0，就是寫2,1,0，然後0寫值為0。是找1，就是寫2,1，然後1寫值為1。是找2，就是寫2，然後2寫值為2。）
這樣一路判斷下去，可以排序。
“`
// Q75. Sort Colors
public void sortColors(int[] nums) {
int zero = –1;
int one = –1;
int two = –1;
for (final int num : nums) {
if (num == 0) {
nums[++two] = 2;
nums[++one] = 1;
nums[++zero] = 0;
} else if (num == 1) {
nums[++two] = 2;
nums[++one] = 1;
} else {
nums[++two] = 2;
}
}
}
“`
