数组中最大的子数组之和

一.程序分析

1.使用Python语言进行编译程序，求数组中的最大子数组之和

输入，一个数组，和它的大小

输出，这个数组中最大子数组的和

 

 

 

Python代码段:

#定义变量
num = 0
strNum = ""
lis = []
lis1 = []

#获取输入内容
string = input("请输入数组数据,以‘.’隔开,以Enter结束：")

#将获取到的内容转换成为数组
for i in string:
    if ord("9") >= ord(i) >= ord("0") or ord(i) == ord("-"):
        strNum = strNum + i
    else:
        lis.append(int(strNum))
        strNum = ""
lis.append(int(strNum))
strNum = ""

#将单个的子数组先放入新数组内

for i in lis:
    lis1.append(int(i))

#将其余组合得到的和放入新数组
sumnum = 0
for i in range(2, len(lis) + 1):
    for k in range(0, len(lis) - i + 1):
        for j in range(i):
            sumnum = sumnum + int(lis[k + j])
        lis1.append(int(sumnum))
        sumnum = 0

#找出最大值
maxNumber = 0
for i in lis1:
    if i >= maxNumber:
        maxNumber = i

print("maxNumber:"+maxNumber)

运行结果:

 2.从文本文件中读输入的数据，熟悉文件操作， 文件有两种数据

第一个数字：这次测试中有多少个数据， 数字后面是冒号。

后续数字： 每个数据的值，用逗号隔开

文件内容： 17: -32, -10, 33, -23, 32, -12, 41, -12, 1, 3, 5, -98, 70, -21, 10, -9, 61

输出 sum = 71

Python代码段:

#定义变量

num = 0
strNum = ""
lis1 = []
lis2 = []
#读取文件内容
with open('text.txt', 'r', encoding='utf-8') as f:
    string = f.read()
　　 print(string)

#将获取到的内容转换成为数组

for i in string:
    if ord(i) == ord(" "):
        continue
    if ord("9") >= ord(i) >= ord("0") or ord(i) == ord("-"):
        strNum = strNum + i
    else:
        lis1.append(int(strNum))
        strNum = ""
lis1.append(int(strNum))
strNum = ""

#将获取到的内容转换成为数组

for i in lis1:
    lis2.append(int(i))

#将其余组合得到的和放入新数组

sumnum = 0
for i in range(2, len(lis1) + 1):
    for k in range(0, len(lis1) - i + 1):
        for j in range(i):
            sumnum = sumnum + int(lis1[k + j])
        lis2.append(int(sumnum))
        sumnum = 0
#找出最大值
maxNumber = 0
for i in lis2:
    if i >= maxNumber:
        maxNumber = i

print("maxNumber:"+str(maxNumber))

运行结果:

 

 3.用类/函数来实现.

需求：希望返回 3 种信息

1.最大子数组的和

2.最大子数组开始的下标

3.最大子数组结束的下标

 

Python代码段:

def ReadFile(Path):
    with open(Path, 'r', encoding='utf-8') as f:
        return f.read()


class MaxNumber:
    maxNumber = 0
    startSite = endSite = ""
    string = "NULL"
    List1 = []

    def __init__(self, strings):
        self.string = strings

    def CreateList(self):
        strNum = ""
        for i in self.string:
            if ord(i) == ord(" "):
                continue
            if ord("9") >= ord(i) >= ord("0") or ord(i) == ord("-"):
                strNum = strNum + i
            else:
                self.List1.append(int(strNum))
                strNum = ""
        self.List1.append(int(strNum))

    def FindMaxNumber(self):
        sumnum = 0
        length = len(self.List1)
        for i in range(2, length + 1):
            for k in range(0, length - i + 1):
                for j in range(i):
                    sumnum = sumnum + int(self.List1[k + j])
                self.List1.append([sumnum, k, k + i - 1])
                sumnum = 0

    def format(self):
        count = 0
        for i in self.List1:
            if isinstance(i, int):
                self.List1[count] = [i, count, count]
                count = count + 1

    def ShowMax(self):
        self.CreateList()
        self.FindMaxNumber()
        self.format()
        for i in self.List1:
            if i[0] >= self.maxNumber:
                self.maxNumber = i[0]
                self.startSite = i[1]
                self.endSite = i[2]
        print("最大的子元组之和为:" + str(self.maxNumber))
        print("起始位置为:" + str(self.startSite))
        print("结束位置为:" + str(self.endSite))


if __name__ == '__main__':
    # 定义变量
    string = ""
    # 读取文件内容
    filePath = "text.txt"
    string = ReadFile(filePath)
    # 实例化
    maxnum = MaxNumber(string)
    maxnum.ShowMax()
运行结果: