软件工程第三次作业

1.题目要求
问题： 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。
2.编写代码
代码托管所地址：
最大子段和

#include<stdio.h>
#include<stdlib.h>
int maxsub(int a[], int w);
int main()
{
	int a[1000], w=0, i, m;
	scanf("%d", &w);
	for (i = 0; i < n; i++)
	{
		scanf("%d", &a[i]);
	}
	m = maxsub(a, w);
	if (m == -1)
		printf("输入错误，请检查后重新输入");
	else
		printf("最大字段和为%d", m);
	printf("\n");
	system("pause");
	return 0;
}
int maxsub(int a[], int w)
{
	int i = 0, Sum=0, Max=0;
	if (w == 0)
		Max = 0;
	else if (w < 0)
		Max = -1;
	else if(w>0)
	{
		for (i = 0; i < w; i++)
		{
			Sum = Sum + a[i];
			if (Sum > Max)
				Max = Sum;
			if (Sum <= 0)
				Sum = 0;
		}
	}
	return Max;
}

3.2编写测试代码

``` #include "stdafx.h" #include "CppUnitTest.h"

using namespace Microsoft::VisualStudio::CppUnitTestFramework;
int maxsub(int a[], int w)
{
int i = 0, Sum = 0, Max = 0;
if (w == 0)
Max = 0;
else if (w < 0)
Max = -1;
else if (w > 0)
{
for (i = 0; i < w; i++)
{
Sum = Sum + a[i];
if (Sum > Max)
Max = Sum;
if (Sum <= 0)
Sum = 0;
}
}
return Max;
}
namespace UnitTest1
{
TEST_CLASS(UnitTest1)
{
public:

	TEST_METHOD(TestMethod1)
	{
		int a[6] = { -2,11,-4,13,-5,-2 };
		int m = 0;
		m = maxsub(a, 6);
		Assert::AreEqual(m, 20);
	}
	TEST_METHOD(TestMethod2)
	{
		int a[] = { 0 };
		int m = 0;
		m = maxsub(a, 0);
		Assert::AreEqual(m, 0);
	}
	TEST_METHOD(TestMethod3)
	{
		int a[6] = { -2,-1,-4,-3,-100,-2 };
		int m = 0;
		m = maxsub(a, 6);
		Assert::AreEqual(m, 0);
	}
	TEST_METHOD(TestMethod4)
	{
		int a[6] = { -2,11,-4,13,-5,-2 };
		int m = 0;
		m = maxsub(a, -2);
		Assert::AreEqual(m, -1);
	}
};

}

![](https://img2018.cnblogs.com/blog/1650532/201904/1650532-20190419093337109-1618266669.png)
![](https://img2018.cnblogs.com/blog/1650532/201904/1650532-20190419093343147-2120590771.png)