Given an array 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.
Here, we will use the integers 0, 1, and 2 to represent the color red, white, and blue respectively.
Example：
Input: [2,0,2,1,1,0]
Output: [0,0,1,1,2,2]
Note：
You are not suppose to use the library's sort function for this problem.
解释下题目：
数组中只有三种元素，在这个前提下进行排序
1. 特殊优化法
实际耗时：0ms
public void sortColors(int[] nums) {
//把三种颜色记下来就行了
int num1 = 0;
int num2 = 0;
int num3 = 0;
for (int i = 0; i < nums.length; i++) {
if (0 == nums[i]) {
num1++;
} else if (1 == nums[i]) {
num2++;
} else {
num3++;
}
}
//然后把数组搞一下就行了
for (int i = 0; i < num1; i++) {
nums[i] = 0;
}
for (int i = num1; i < num1 + num2; i++) {
nums[i] = 1;
}
for (int i = num1 + num2; i < nums.length; i++) {
nums[i] = 2;
}
}
思路：既然只有三个数字，那我每个数字出现了几次记下来，然后在对数组进行处理就行了。这里很容易思维定式，想到排序去。
