public void sortColors(int[] nums) {
if (nums == null || nums.length == 0) return;
int left = 0;
int right = nums.length - 1;
int index = 0;
while (index <= right) {
if (nums[index] == 0) {
swap(nums, index++, left++);
} else if (nums[index] == 1) {
index++;
} else {
swap(nums, index, right--);
}
}
}
public void swap(int[] nums, int i, int j) {
int temp = nums[i];
nums[i] = nums[j];
nums[j] = temp;
}
