LeetCode_Sort Colors

最新推荐文章于 2024-11-13 23:54:20 发布

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最新推荐文章于 2024-11-13 23:54:20 发布

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本文介绍了一种不使用标准库排序函数的特殊排序算法——三色排序。该算法将数组中的红（0）、白（1）、蓝（2）三种颜色元素进行排序，确保相同颜色的元素相邻且按红、白、蓝的顺序排列。通过两个指针 p0 和 p1 来跟踪已排序部分的边界，有效地实现了原地排序。

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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.

class Solution {
public:
    void sortColors(int arr[], int n) {
        // Start typing your C/C++ solution below
        // DO NOT write int main() function
        if (arr == NULL || n <= 0)
            return;
        int p0 = 0;
        int p1 = 0;
        for (int i = 0; i < n; ++i)
        {
            if (arr[i] == 0)
            {
                if (p0 != i)
                {
                    SwapInt(arr[i], arr[p0]);                    
                }
                ++p0;
                if (p0 > p1)
                {
                    p1 = p0;
                }
            }
            if (arr[i] == 1)
            {
                if (p1 != i)
                {
                    SwapInt(arr[i], arr[p1]);                    
                }
                ++p1;
            }
        }
    }
    void SwapInt(int &a, int &b)
    {
        int tmp = a;
        a = b;
        b = tmp;
    }
};