C++11写算法之顺序查找

从这篇博文起，将尝试使用C++11来写常用算法与数据结构。

本篇博文以最简单的顺序查找作为系列博文的起点，并作约定如下：

1，变量名 ： varList ； 函数名 : SequentialFind ;

2，尽量描写算法本身，因而均不含模板，数据类型均为int；

3，所有代码均在同一个cpp中；

4，代码均在 vs2013 与 g++ 4.8.2 中编译通过；

5，g++编译命令：g++ -std=c++11 sequential_find.cpp 。

 

顺序查找没什么好说的，这里主要看看C++11的lambda，auto新语义。

时间复杂度：O(n)

空间复杂度：O(1)

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;



int SequentialFind(const int varList[], const int size, const int target)

{

    if (!varList || size < 0)

    {

        return -1;

    }

    int index = -1;

    for (int i = 0; i < size;i++)

    {

        if (varList[i] == target)

        {

            index = i;

            break;

        }

    }

    return index;

}



void test()

{

    //case counter

    int testCase = 0;

    //find function object

    auto findFunc = SequentialFind;

    //show case result lambda function

    auto showFunc = [&testCase](){cout << "case[" << testCase++ << "] ok... "<<endl; };



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



    //case empty list

    {

        assert(-1 == findFunc(nullptr, 0, 0));

        showFunc();

    }

    //case wrong list size

    {

        const int testList[] = { 11,5,7,9,3, 2, 3 ,4,1,-2};

        assert(-1 == findFunc(testList, 0, 0));

        showFunc();

    }

    //case not found

    {

        const int testList[] = { 11, 5, 7, 9, 3, 2, 3, 4, 1, -2 };

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

        const int target = -33;

        assert(-1 == findFunc(testList, 0, 0));

        showFunc();

    }

    //case found at begin position

    {

        const int testList[] = { 11, 5, 7, 9, 3, 2, 3, 4, 1, -2 };

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

        const int target = 11;

        assert(0 == findFunc(testList, size, target));

        showFunc();

    }

    //case found at random position

    {

        const int testList[] = { 11, 5, 7, 9, 3, 2, 3, 4, 1, -2 };

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

        const int target = 9;

        assert(3 == findFunc(testList, size, target));

        showFunc();

    }

    //case found at end position

    {

        const int testList[] = { 11, 5, 7, 9, 3, 2, 3, 4, 1, -2 };

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

        const int target = -2;

        assert(size - 1 == findFunc(testList, size, target));

        showFunc();

    }



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

}



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

{

    test();

    return 0;

}