C++11写算法之冒泡排序

冒泡排序很形象，指从数组后面将更小的值慢慢浮到前面去，每遍历一趟使得最小值浮到最前面（指当前位置）。

这里有点小技巧，当某一次遍历过程中发现无交换，则说明此时数组已经排序完成，可提前退出。

时间复杂度：O(n^2)

空间复杂度：O(1)

此处应用了C++11的auto , lambda , static_assert 。

show me the code ！

// #if __cplusplus < 201103L 

// #error "must be compiled under c++11 support platform!!!"

// #endif

#include <iostream>

#include <algorithm>

#include <iterator>

#include <cassert>

using namespace std;



void Swap(int& a, int& b)

{

    int tmp = a;

    a = b;

    b = tmp;

}

void BubbleSort(int varList[], const int size)

{

    if (!varList || size <= 1)

    {

        return;

    }

    bool sortedOK = false;

    for (int i = 0; i < size && !sortedOK; i++)

    {

        sortedOK = true;

        for (int j = size - 1; j >= i;j--)

        {

            if (varList[j-1] > varList[j])

            {

                Swap(varList[j - 1], varList[j]);

                sortedOK = false;

            }

        }

    }

}



void test()

{

    //case counter

    int testCase = 0;

    //sort function object

    auto sortFunc = BubbleSort;

    //show case result lambda function

    auto showFunc = [&testCase](const char* caseDescription){cout << "case[" << testCase++ << "]\t(" << caseDescription << ") \t\tok " << endl; };



    cout << "test begin : " << endl << endl;



    //case empty list

    {

        sortFunc(nullptr, 0);

        showFunc("case empty list");

    }

    //case wrong size

    {

        int nTestList[] = { 13, 52, 32, 15, 66, 2, 99, 202, 103, 2 };

        sortFunc(nTestList, 0);

        showFunc("case wrong size");

    }

    //case size == 1

    {

        int var = 13;

        int varList[] = { var };

        sortFunc(varList, 1);

        assert(var == varList[0]);

        showFunc("case size == 1");

    }

    //case normal sort

    {

        int varList[] = { 13, 52, 32, 15, 66, 2, 99, 202, 103, 2 };

        const int size = sizeof(varList) / sizeof(int);

        const int resultList[] = { 2, 2, 13, 15, 32, 52, 66, 99, 103, 202 };

        static_assert(sizeof(varList) == sizeof(resultList),"size of varList is not equal with resultList!!");



        sortFunc(varList, size);

        for (int i = 0; i < size; i++){ assert(varList[i] == resultList[i]); }

        showFunc("case normal sort");

    }

    //case sorted list

    {

        int varList[] = { 2, 2, 13, 15, 32, 52, 66, 99, 103, 202 };

        const int size = sizeof(varList) / sizeof(int);

        const int resultList[] = { 2, 2, 13, 15, 32, 52, 66, 99, 103, 202 };

        static_assert(sizeof(varList) == sizeof(resultList), "size of varList is not equal with resultList!!");



        sortFunc(varList, size);

        for (int i = 0; i < size; i++){ assert(varList[i] == resultList[i]); }

        showFunc("case sorted list");

    }

    cout << endl << "test done ! " << endl << endl;

}

int main(int argc, char* argv[])

{

    test();

    return 0;

}