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 either 0, 1, or 2.
Follow up: Could you come up with a one-pass algorithm using only constant extra space?
class Solution {
public:
void sortColors(vector<int>& nums) {
int lt=0, rt=nums.size()-1, mid=lt;
while(mid<=rt){
switch(nums[mid]){
case 0:
swap(nums[lt++],nums[mid++]);
break;
case 1:
mid++;
break;
case 2:
swap(nums[mid],nums[rt--]);
break;
}
}
}
};class Solution {
public void sortColors(int[] nums) {
int[] colorsFreq = new int[3];
for (int i : nums)
colorsFreq[i]++;
for (int c = 0, i = 0; c < 3; c++)
while (colorsFreq[c]-- > 0)
nums[i++] = c;
}
}