Star

LeetCode 75.Sort Colors

Posted on | In |

Question

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.

Explanation

这道题，需要一个指针一直在遍历数组。同时，还有left，和right两个指针分别计算0和2。

Code

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
public class Solution {
    public void sortColors(int[] nums) {
        int j = 0, k = nums.length-1;
        for (int i=0; i <= k; i++) {
            if (nums[i] == 0)
                swap(nums, i, j++);
            else if (nums[i] == 2)
                swap(nums, i--, k--);
        }
    }
    private void swap(int[] a, int i, int j) {
        int tmp = a[i];
        a[i] = a[j];
        a[j] = tmp;
    }
}