LeetCode 75 Sort Colors

Given an array with n objects colored red, white or blue, sort them 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.

Note:

You are not suppose to use the library's sort function for this problem.

方法一：

public void sortColors(int[] nums) {
int red = 0, blue = nums.length - 1, i = 0;
while (i <= blue) {
int tmp;
/**0排到前面,2排到后面*/
if (nums[i] == 0) {
tmp = nums[i];
nums[i++] = nums[red];
nums[red++] = tmp;
} else if (nums[i] == 2) {
tmp = nums[i];
nums[i] = nums[blue];
nums[blue--] = tmp;
} else i++;
}
}


方法二：
public void sortColors2(int[] nums) {
int[] count = new int[3];
for (int i = 0; i < nums.length; i++)
count[nums[i]]++;
for (int i = 0, index = 0; i < 3; i++)
for (int j = 0; j < count[i]; j++)
nums[index++] = i;
}
方法三：
public void sortColors3(int[] nums) {
int l = 0, m = 0, n = 0;
for (int i = 0; i < nums.length; i++) {
if (nums[i] == 0) {
nums[n++] = 2;
nums[m++] = 1;
nums[l++] = 0;
} else if (nums[i] == 1) {
nums[n++] = 2;
nums[m++] = 1;
} else nums[n++] = 2;
}
}