LeetCode in Net
75. Sort Colors
Medium
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]
Example 3:
Input: nums = [0]
Output: [0]
Example 4:
Input: nums = [1]
Output: [1]
Constraints:
n == nums.length1 <= n <= 300nums[i]is0,1, or2.
Follow up: Could you come up with a one-pass algorithm using only constant extra space?
Solution
public class Solution {
public void SortColors(int[] nums) {
int zeroes = 0;
int ones = 0;
for (int i = 0; i < nums.Length; i++) {
if (nums[i] == 0) {
nums[zeroes++] = 0;
} else if (nums[i] == 1) {
ones++;
}
}
for (int j = zeroes; j < zeroes + ones; j++) {
nums[j] = 1;
}
for (int k = zeroes + ones; k < nums.Length; k++) {
nums[k] = 2;
}
}
}