Sort Colors

最新推荐文章于 2021-04-15 12:30:39 发布

最新推荐文章于 2021-04-15 12:30:39 发布 · 55 阅读

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本文介绍了一种不使用标准库排序函数来对红、白、蓝三种颜色进行排序的方法。通过荷兰国旗问题的经典解决方案，实现了一个原地排序算法，该算法仅使用常数级额外空间，适合于整型数组中0、1、2的排序。

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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.

public class Solution {
    public void sortColors(int[] nums) {
        if (nums == null || nums.length < 2) {
        	return;
        }
        int left = -1;
        int index = 0;
        int right = nums.length;
        while (index < right) {
        	if (nums[index] == 0) {
        		swap(nums, ++left, index++);
        	} else if (nums[index] == 2) {
        		swap(nums, index, --right);
        	} else {
        		index++;
        	}
        }
    }

	private void swap(int[] nums, int i, int j) {
		// TODO Auto-generated method stub
		int tmp = nums[i];
		nums[i] = nums[j];
		nums[j] = tmp;
	}
}