软件工程第三次作业-1605班05赵一霖
一、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。
二、编写程序
Coding.net地址:https://dev.tencent.com/u/dtid_5e821d7aa22635d9/p/zuidalianxuzishuzuhe/git/tree/master
package homework2;
import java.util.Scanner;
public class main
{
public void mainn(String[] args)
{
Scanner inport=new Scanner(System.in);
int i,n;
int[] num=new int[100];
n=inport.nextInt();
for(i=0;i<n;i++)
num[i]=inport.nextInt();
int result = sum(num);
System.out.println("连续子元素的最大和为:"+result);
inport.close();
}
public int sum(int[] num)
{
if (num.length==0 || num==null)
{
return 0;
}
int currentSum = 0;
int max = 0;
for (int i = 0; i <num.length; i++)
{
if(currentSum<=0)
{
currentSum = num[i];
}
else
{
currentSum = currentSum + num[i];
}
if(currentSum>max)
{
max = currentSum;
}
}
return max;
}
}
三、程序流程图
四、判定/条件覆盖测试
测试需要包括以下情况:
数组num为空 | currentSum<=0 | currentSum>max |
---|---|---|
数组num不为空 | currentSum>0 | currentSum<=max |
测试代码:
package homework2;
import static org.junit.Assert.*;
import org.junit.Test;
public class test
{
@Test
public void sum1() {
assertEquals(0, new main().sum(new int[] {} ));
}
@Test
public void sum2() {
assertEquals(20,new main().sum(new int[] {-2,11,-4,13,-5,-2} ));
}
@Test
public void sum3() {
assertEquals(0, new main().sum(new int[] {-1,-2,-3,-4,-5,-6} ));
}
@Test
public void sum4() {
assertEquals(12, new main().sum(new int[] {1,4,7} ));
}
}