软件工程——第三次做业

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本项目发布在在腾讯云代码托管平台（即Coding.net）

1. 题目

最大连续子数组和（最大子段和）

给定n个整数（可能为负数）组成的序列a[1],a[2],a[3],…,a[n],求该序列如a[i]+a[i+1]+…+a[j]的子段和的最大值。当所给的整数均为负数时定义子段和为0，依此定义，所求的最优值为： Max{0,a[i]+a[i+1]+…+a[j]},1<=i<=j<=n 例如，当（a[1],a[2],a[3],a[4],a[5],a[6]）=(-2,11,-4,13,-5,-2)时，最大子段和为20。 ———引用自百度百科

2. 设计程序

使用C ++语言编写所须要的程序

首先编写主程序Max SubSequence Sum.cpp

// Max SubSequence Sum.cpp : 此文件包含 "main" 函数。程序执行将在此处开始并结束。
//

#include "pch.h"
#include <iostream>
#include "sumlib.h"

using namespace std;

int main()
{
	const int aArray[] = { -2,-11,-4,-13,-5,-2 };
	int iLength = sizeof(aArray) / sizeof(aArray[0]);
	int maxSSSum = MaxSubSequenceSum(aArray, iLength);
	cout << "The Max Sub-sequence summary of this array is: " << maxSSSum << endl;
	system("pause");
	return 0;
}

再编写头文件sumlib.h

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

int MaxSubSequenceSum(const int *array, int cntLength)
{
	if (array == NULL || cntLength <= 0)
	{
		return 0;
	}
	int tempSum, maxSum;
	maxSum = 0;
	for (int cntI = 0; cntI < cntLength; cntI++)
	{
		tempSum = 0;
		for (int cntJ = cntI; cntJ < cntLength; cntJ++)
		{
			tempSum += array[cntJ];
			if (tempSum > maxSum)
			{
				maxSum = tempSum;
			}
		}
	}
	return maxSum;
}

程序运行的结果如图所示

#3. 选择覆盖标准并设计测试样例 咱们选择断定/条件覆盖来设计测试样例

所设计的程序中求最大子段和的函数

int MaxSbuSequence(const int *array, int cntLength)

的流程图为

根据流程图，咱们能够看出，若想知足断定/条件覆盖，则需知足下列条件

• 数组为空 或 长度≤0 ？
  • 数组为空，长度 ≤ 0，T1断定为True
  • 数组为空，长度 > 0， T1断定为True
  • 数组不为空，长度 ≤ 0， T1断定为True
  • 数组不为空，长度 > 0， T1断定为False
• tempSum > maxSum ?
  • tempSum > maxSum，T2断定为True
  • tempSum < maxSum，T2断定为Flase
• cntJ < cntLength ?
  • cntJ < cntLength，T3断定为True
  • cntJ > cntLength，T3断定为Flase
• cntI < cntLength ?
  • cntI < cntLength，T4断定为True
  • cntI > cntLength，T4断定为Flase

断定3和断定4为循环控制过程当中的判断，每次执行程序均会经历T = true和T = fasle，所以无需对这两个断定设计测试样例。

根据以上条件咱们能够得出以下的测试样例：

<table border=0 cellpadding=0 cellspacing=0 width=959 style='border-collapse: collapse;table-layout:fixed;width:719pt'> <col class=xl66 width=64 span=3 style='width:48pt'> <col class=xl66 width=244 style='mso-width-source:userset;mso-width-alt:8675; width:183pt'> <col class=xl66 width=267 style='mso-width-source:userset;mso-width-alt:9500; width:200pt'> <col class=xl66 width=128 style='mso-width-source:userset;mso-width-alt:4551; width:96pt'> <col class=xl66 width=64 span=2 style='width:48pt'> <tr height=19 style='height:14.4pt'> <td rowspan=2 height=38 class=xl67 width=64 style='height:28.8pt;width:48pt'><font class="font9">序号</font></td> <td colspan=2 class=xl67 width=128 style='border-left:none;width:96pt'>T1</td> <td class=xl67 width=244 style='border-left:none;width:183pt'>T2</td> <td rowspan=2 class=xl67 width=267 style='width:200pt'><font class="font9">路径</font></td> <td colspan=2 class=xl67 width=192 style='border-left:none;width:144pt'><font class="font9">样例</font></td> <td rowspan=2 class=xl67 width=64 style='width:48pt'><font class="font9">指望值</font></td> </tr> <tr height=19 style='height:14.4pt'> <td height=19 class=xl67 style='height:14.4pt;border-top:none;border-left: none'><font class="font9">数组为空</font></td> <td class=xl67 style='border-top:none;border-left:none'><font class="font9">长度≤</font><font class="font8">0</font></td> <td class=xl67 style='border-top:none;border-left:none'>tempSum&gt;maxSum</td> <td class=xl67 style='border-top:none;border-left:none'><font class="font9">数组</font></td> <td class=xl67 style='border-top:none;border-left:none'><font class="font9">长度</font></td> </tr> <tr height=19 style='height:14.4pt'> <td height=19 class=xl65 style='height:14.4pt;border-top:none'>1</td> <td class=xl65 style='border-top:none;border-left:none'>T</td> <td class=xl65 style='border-top:none;border-left:none'>T</td> <td class=xl65 style='border-top:none;border-left:none'>T1<font class="font6">为</font><font class="font7">T</font><font class="font6">，则路径不通过</font><font class="font7">T2</font></td> <td class=xl65 style='border-top:none;border-left:none'>START<font class="font6">→</font><font class="font7">B</font><font class="font6">→</font><font class="font7">END</font></td> <td class=xl65 style='border-top:none;border-left:none'>{ }</td> <td class=xl65 style='border-top:none;border-left:none'>0</td> <td class=xl65 style='border-top:none;border-left:none'>0</td> </tr> <tr height=18 style='height:13.8pt'> <td height=18 class=xl65 style='height:13.8pt;border-top:none'>2</td> <td class=xl65 style='border-top:none;border-left:none'>F</td> <td class=xl65 style='border-top:none;border-left:none'>F</td> <td class=xl65 style='border-top:none;border-left:none'>F</td> <td class=xl65 style='border-top:none;border-left:none'>START→A→C<font class="font10">→</font><font class="font7">D</font><font class="font10">→</font><font class="font7">……→END</font></td> <td class=xl65 style='border-top:none;border-left:none'>{ -5,-6,-1,-3 }</td> <td class=xl65 style='border-top:none;border-left:none'>4</td> <td class=xl65 style='border-top:none;border-left:none'>0</td> </tr> <tr height=18 style='height:13.8pt'> <td height=18 class=xl65 style='height:13.8pt;border-top:none'>3</td> <td class=xl65 style='border-top:none;border-left:none'>F</td> <td class=xl65 style='border-top:none;border-left:none'>F</td> <td class=xl65 style='border-top:none;border-left:none'>T</td> <td class=xl65 style='border-top:none;border-left:none'>START→A<font class="font10">→</font><font class="font7">D</font><font class="font10">→</font><font class="font7">……</font><font class="font10">→</font><font class="font7">END</font></td> <td class=xl65 style='border-top:none;border-left:none'>{<span style='mso-spacerun:yes'>&nbsp; </span>3,7,2,27,3 }</td> <td class=xl65 style='border-top:none;border-left:none'>5</td> <td class=xl65 style='border-top:none;border-left:none'>42</td> </tr> <tr height=19 style='height:14.4pt'> <td height=19 class=xl65 style='height:14.4pt;border-top:none'>4</td> <td class=xl65 style='border-top:none;border-left:none'>F</td> <td class=xl65 style='border-top:none;border-left:none'>F</td> <td class=xl65 style='border-top:none;border-left:none'><font class="font6">在循环过程当中经历了</font><font class="font7">T</font><font class="font6">和</font><font class="font7">F</font><font class="font6">两种断定</font></td> <td class=xl65 style='border-top:none;border-left:none'>START→A<font class="font10">→</font><font class="font7">C</font><font class="font10">→</font><font class="font7">D</font><font class="font10">→</font><font class="font7">……</font><font class="font10">→</font><font class="font7">A</font><font class="font10">→</font><font class="font7">D</font><font class="font10">→</font><font class="font7">END</font></td> <td class=xl65 style='border-top:none;border-left:none'>{ -2,11,-4,13,-5,-2 }</td> <td class=xl65 style='border-top:none;border-left:none'>6</td> <td class=xl65 style='border-top:none;border-left:none'>20</td> </tr> <![if supportMisalignedColumns]> <tr height=0 style='display:none'> <td width=64 style='width:48pt'></td> <td width=64 style='width:48pt'></td> <td width=64 style='width:48pt'></td> <td width=244 style='width:183pt'></td> <td width=267 style='width:200pt'></td> <td width=128 style='width:96pt'></td> <td width=64 style='width:48pt'></td> <td width=64 style='width:48pt'></td> </tr> <![endif]> </table>

4. 测试和结果

设计测试程序的代码

#include "stdafx.h"
#include "CppUnitTest.h"
#include "..\Max SubSequence Sum\sumlib.h"

using namespace Microsoft::VisualStudio::CppUnitTestFramework;

namespace UnitTest1
{		
	TEST_CLASS(UnitTest1)
	{
	public:
		
		TEST_METHOD(TestMethod1)
		{
			const int *aArray = {};
			int iLength = sizeof(aArray) / sizeof(aArray[0]);
			Assert::AreEqual(MaxSubSequenceSum(aArray, iLength), 0);
		}

		TEST_METHOD(TestMethod2)
		{
			const int aArray[] = { -5,-6,-1,-3 };
			int iLength = sizeof(aArray) / sizeof(aArray[0]);
			Assert::AreEqual(MaxSubSequenceSum(aArray, iLength), 0);
		}

		TEST_METHOD(TestMethod3)
		{
			const int aArray[] = { 3,7,2,27,3 };
			int iLength = sizeof(aArray) / sizeof(aArray[0]);
			Assert::AreEqual(MaxSubSequenceSum(aArray, iLength), 42);
		}

		TEST_METHOD(TestMethod4)
		{
			const int aArray[] = { -2,11,-4,13,-5,-2 };
			int iLength = sizeof(aArray) / sizeof(aArray[0]);
			Assert::AreEqual(MaxSubSequenceSum(aArray, iLength), 20);
		}

	};
}

测试结果如图所示