homework-02 "最大子数组之和"的问题进阶

代码编写

这次的作业瞬间难了好多，无论是问题本身的难度或者是单元测试这一原来没接触过的概念或者是命令行参数的处理这些琐碎的问题，都使得这次作业的完成说不上轻松。

最大子数组之和垂直水平相连的拓展问题解决关键在于循环语句的适度改写，连通问题则是用递归搜索的方法来解决（效率没有实测），在15*15的情况下还是能较快得出结果的。

非常庆幸使用的是Python，Pyhton中很多语法能够保证我在编写代码时不用分太多的时间去处理数据输入，在处理问题上一些数组相关灵活的语法也很大程度上方便了代码的编写。

 # coding:utf-8
 '''
 2013-9-30  XTH
 '''
 import sys

 def setglobalvar():
     global max_sum,now_sum,min_x,min_y,num,visited,pointgroup
     max_sum = 0
     now_sum = 0
     min_x = 0
     min_y = 0
     num = []
     visited = {}
     pointgroup = []

 def maxsum_h(num,n1,n2):#水平上相连
     line = [0]*n2
     max_sum = 0     #最大和
     now_sum = 0     #当前和
     for l in range (0,n2):
         for i in range(0,n1):
             for j in range(i,n1):
                 for k in range(0+l,n2+l):
                     k = k % n2
                     line[k] += num[j][k]
                     if now_sum <0:
                         now_sum = 0
                     now_sum += line[k]
                     if now_sum > max_sum:
                         max_sum = now_sum
                 now_sum = 0
             now_sum=0
             line = [0]*n2
     return max_sum

 def maxsum_v(num,n1,n2):    #垂直上相连
     line = [0]*n2
     max_sum = 0     #最大和
     now_sum = 0     #当前和
     for l in range (0,n1):
         for i in range(0,n1):
             for j in range(i+l,n1+l):
                 for k in range(0,n2):
                     j = j % n1
                     line[k] += num[j][k]
                     if now_sum <0:
                         now_sum = 0
                     now_sum += line[k]
                     if now_sum > max_sum:
                         max_sum = now_sum
                 now_sum = 0
             now_sum=0
             line = [0]*n2
     return max_sum

 def maxsum(num,n1,n2):#普通
     line = [0]*n2
     max_sum = 0     #最大和
     now_sum = 0     #当前和
     for i in range(0,n1):
         for j in range(i,n1):
             for k in range(0,n2):
                 line[k] += num[j][k]
                 if now_sum <0:
                     now_sum = 0
                 now_sum += line[k]
                 if now_sum > max_sum:
                     max_sum = now_sum
             now_sum = 0
         now_sum=0
         line = [0]*n2
     return max_sum

 def maxsum_vh(num,n1,n2):#垂直水平相连
     line = [0]*n2
     max_sum = 0     #最大和
     now_sum = 0     #当前和
     for l1 in range (0,n1):
         for l2 in range (0,n2):
             for i in range(0,n1):
                 for j in range(i+l1,n1+l1):
                     for k in range(0+l2,n2+l2):
                         j = j % n1
                         k = k % n2
                         line[k] += num[j][k]
                         if now_sum <0:
                             now_sum = 0
                         now_sum += line[k]
                         if now_sum > max_sum:
                             max_sum = now_sum
                     now_sum = 0
                 now_sum=0
                 line = [0]*n2
     return max_sum

 def searchthrough(x,y,num,now_sum):#搜索函数
     global max_sum,pointgroup,min_x,min_y,visited
     max_sum = max(max_sum, now_sum)
     for i in [[0,-1],[1,0],[0,1],[-1,0]]:
         if x+i[0]>=min_x and x+i[0]<n1 and y+i[1]>=min_y and y+i[1]<n2 and visited[(x+i[0])%n1,(y+i[1])%n2]==0 and [(x+i[0])%n1,(y+i[1])%n2,num[(x+i[0])% n1][(y+i[1])%n2]] not in pointgroup:
             pointgroup.append([(x + i[0]) % n1, (y + i[1]) % n2, num[(x + i[0]) % n1][(y + i[1]) % n2]])
     if pointgroup == []:
         return
     pointgroup = sorted(pointgroup, key=lambda x: x[2])
     nextpoint = pointgroup.pop()
     if now_sum + nextpoint[2] > 0:
         visited[nextpoint[0], nextpoint[1]] = 1
         searchthrough(nextpoint[0],nextpoint[1],num,now_sum + nextpoint[2])
         visited[nextpoint[0], nextpoint[1]] = 0
     else:
         return

 def maxsum_a(num,n1,n2):    #连通
     global min_x,min_y,max_sum,visited
     min_x = 0
     min_y = 0
     max_sum = 0
     now_sum = 0
     startpointx = []
     startpointy = []
     pointgroup = []
     for i in range(0,n1):
         for j in range(0,n2):
             visited[i,j] = 0
     for i in range(0,n1):
         for j in range(0,n2):
             if num[i][j] > 0:
                 startpointx.append(i)
                 startpointy.append(j)
     for pointx in startpointx:
         pointy = startpointy.pop()
         visited[pointx, pointy] = 1
         searchthrough(pointx,pointy,num,num[pointx][pointy])
     return max_sum

 def maxsum_vha(num,n1,n2):    #水平垂直上相连 连通
     global min_x,min_y,max_sum,visited
     min_x = -n1
     min_y = -n2
     max_sum = 0
     now_sum = 0
     startpointx = []
     startpointy = []
     pointgroup = []
     for i in range(0,n1):
         for j in range(0,n2):
             visited[i,j] = 0
     for i in range(0,n1):
         for j in range(0,n2):
             if num[i][j] > 0:
                 startpointx.append(i)
                 startpointy.append(j)
     for pointx in startpointx:
         pointy = startpointy.pop()
         visited[pointx, pointy] = 1
         searchthrough(pointx,pointy,num,num[pointx][pointy])
     return max_sum

 def main():
     setglobalvar()
     global n1,n2
     max_sum = 0
     V = H = A = False
     if "\\v" in sys.argv[1:]:
         V = True;
     if "\\h" in sys.argv[1:]:
         H = True;
     if "\\a" in sys.argv[1:]:
         A = True;
     filename = sys.argv[-1];
     try:
         f = open(filename,"r")
     except:
         raise IOError("ERROR:can't open the file")
     try:
         line = f.readline()
         line = line.strip('\n').strip(',')
         n1 = int(line)
         line = f.readline()
         line = line.strip('\n').strip(',')
         n2 = int(line)
         num=[[]]*int(n1)
         for i in range(0,int(n1)):
             line = f.readline()
             line = line.strip('\n')
             if len(line.split(",")) != n2:
                 raise ValueError("ERROR:the format of file is wrong")
             num[i] = line.split(",")
         num=[[int(x) for x in inner] for inner in num]
     except:
         raise ValueError("ERROR:the format of file is wrong")
     if V!=True and H!=True and A == True:#连通
         max_sum = maxsum_a(num,n1,n2);
     elif V==True and H!=True and A != True:#水平上相连
         max_sum = maxsum_v(num,n1,n2);
     elif V!=True and H==True and A != True:#垂直上相连
         max_sum = maxsum_h(num,n1,n2);
     elif V==True and H==True and A != True:#水平垂直上相连
         max_sum = maxsum_vh(num,n1,n2);
     elif V==True and H==True and A == True:#水平垂直上相连连通
         max_sum = maxsum_vha(num,n1,n2);
     else:#普通
         max_sum = maxsum(num,n1,n2);
     return max_sum

 if __name__ == '__main__':
     print main()

单元测试

我大概明白单元测试的概念，但是本次问题很难被看做是一个模块，写单元测试的时候也无从下手，只是简单地测试了一下命令行参数的处理、以及样例的结果验证。

项目时间

PSP2.1	Personal Software Process Stages	Time (%) Senior Student
Planning	计划	6
·         Estimate	·         估计这个任务需要多少时间	6
Development	开发	80
·         Analysis	·         需求分析 (包括学习新技术)	10
·         Design Spec	·         生成设计文档	0
·         Design Review	·         设计复审 (和同事审核设计文档)	0
·         Coding Standard	·         代码规范 (为目前的开发制定合适的规范)	0
·         Design	·         具体设计	15
·         Coding	·         具体编码	40
·         Code Review	·         代码复审	5
·         Test	·         测试（自我测试，修改代码，提交修改）	10
Reporting	报告	14
·         Test Report ·         测试报告		2
·         Size Measurement ·         计算工作量		2
·         Postmortem & Process Improvement Plan ·         事后总结, 并提出过程改进计划		10

总结

由于进入大学之后没有搞过ACM，在解决这个问题的时候非常得吃力，对于群里大家提出的想法也只能是不明觉厉，希望能够在接下来的课程中多多提高吧。