75.Sort Colors（法1快排法2线性扫描统计赋值）

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 inthe 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.

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Array Two
Pointers Sort

#pragma once
#include<iostream>
#include<vector>
using namespace std;

//法1：参数为 数组和数组大小 的快速排序
void sortColors(int A[], int n)
{
	if (n <= 1)
	{
		cout << "return" << endl;
		return;
	}
	int pivot = A[0];
	int begain = 0;
	int end = n - 1;
	while (begain < end)
	{
		while (A[end] >= pivot && end > begain)
			end--;
		A[begain] = A[end];
		while (A[begain] <= pivot&&begain < end)
			begain++;
		A[end] = A[begain];
	}
		A[begain] = pivot;
		sortColors(A, begain);
		sortColors(A + begain + 1, n - begain - 1);
}

//法2：线性扫描，统计次数，重新赋值
void sortColors2(int A[], int n)
{
	int colors[] = { 0, 0, 0 };
	for (int i = 0; i < n; i++)
		colors[A[i]]++;
	int index = 0;
	for (int i = 0; i < 3; i++)
		for (int j = 0; j < colors[i]; j++)
			A[index++] = i;
}

void main()
{
		int A[] = { 1, 2, 2, 2, 2, 0, 0, 0, 1, 1 };
	sortColors2(A, 10);
	for (int i = 0; i < 10; i++)
		cout << A[i] << ' ';
	cout << endl;
	system("pause");
}