一、题目要求
- 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、核心代码
package SumCoding;
import java.util.Scanner;
public class SC {
public static void main(String[] args) {
Scanner scan=new Scanner(System.in);
int i,n;
int[] num=new int[100];
n=scan.nextInt();
for(i=0;i<n;i++)
num[i]=scan.nextInt();
int result = sum(num);
System.out.println("连续子元素的最大和为："+result);
scan.close();
}
public static 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;
}
}
Github代码链接
三、判定/条件覆盖测试程序设计流程图
四、测试样例
public class SCTest {
@Test
public void testSum1() {
assertEquals(0,new SC().sum(new int [] {}));
}
@Test
public void testSum2() {
assertEquals(20,new SC().sum(new int[] {-2,11,-4,13,-5,-2} ));
}
@Test
public void testSum3(){
assertEquals(0, new SC().sum(new int[] {-1,-2,-3,-4,-5,-6} ));
}
}
五、单元测试结果
