算法导论动态规划实现最大子序列

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直接上代码了

#USTC Donglai Ma
#生成两组 六对随机字符串

#生成长度为n的字母串序列

import random
import string
def alphabetran_group(n):
    stralp = ''
    for i in range(n):
        stralp = stralp+random.choice(string.ascii_uppercase)

    return stralp


# print(alphabetran_group(25))
#生成序列 X 的长为 m，序列 Y的长为 n，序列 X 和 Y 的元素从 26个大写字母 中随机生成，m 和 n 的取值：
#    第1组：  (15， 10)， (15， 20)， (15， 30)， (15，40)， (15，50)， (15，60)
#    第2组：  (15， 25)，  (30， 25)，  (45，25)， (60，25)， (75，25)， (90，25)

input_fileA = open("../input/inputA.txt","w")
for i in range(10,61,10):
    input_fileA.write(alphabetran_group(15)+'\n')
    input_fileA.write(alphabetran_group(i)+'\n')
input_fileA.close()

input_fileB = open("../input/inputB.txt","w")
for i in range(15,91,15):
    input_fileB.write(alphabetran_group(i)+'\n')
    input_fileB.write(alphabetran_group(25)+'\n')
input_fileB.close()


#最长子序列算法，参照算法导论
def lcs(a,b):
    lena = len(a)
    lenb = len(b)
    c=[[0 for i in range(lenb+1)] for j in range(lena+1)]
    flag=[[0 for i in range(lenb+1)] for j in range(lena+1)]
    for i in range(lena):
        for j in range(lenb):
            if a[i] == b[j]:
                c[i+1][j+1] = c[i][j]+1
                flag[i+1][j+1]= 'ok'
            elif c[i+1][j]>c[i][j+1]:
                c[i+1][j+1]=c[i+1][j]
                flag[i+1][j+1] = 'left'
            else:
                c[i+1][j+1] = c[i][j+1]
                flag[i+1][j+1]='up'
    return c,flag

def printLcs(flag,a,i,j):
    if i==0 or j==0:
        return
    if flag[i][j] =='ok':

        printLcs(flag,a,i-1,j-1)#意味着是LCS的一个元素
        print(a[i-1],end='')

    elif flag[i][j]=='left':

        printLcs(flag,a,i,j-1)

    else:

        printLcs(flag,a,i-1,j)

    return

# a='ABCBDABCFGMHLS'
# b='BDCABAALGFGGSDG'


#读取文件中第n对字符串
import linecache
def read_fileA(n):

    filenameA = "../input/inputA.txt"
    a = linecache.getline(filenameA,2*n-1)
    #b = fileA.readlines(2*n)
    b = linecache.getline(filenameA,2*n)

    return a,b


def read_fileB(n):

    filenameB = "../input/inputB.txt"
    a = linecache.getline(filenameB,2*n-1)
    #b = fileA.readlines(2*n)
    b = linecache.getline(filenameB,2*n)

    return a,b

import time
import sys
class Logger(object):
    def __init__(self, filename="Default.log"):
        self.terminal = sys.stdout
        self.log = open(filename, "a")

    def write(self, message):
        self.terminal.write(message)
        self.log.write(message)

    def flush(self):
        pass
def calresult_time_A(n):
    a,b = read_fileA(n)
    print("The result of group" +str(n) +"in file_A is ")
    start = time.time()
    c,flag=lcs(a,b)
    end = time.time()
    printLcs(flag,a,len(a),len(b))

    timec = end -start
    outputfile = open("../output/time.txt","a")
    outputfile.write("The time of group"+str(n) +"in file_A is "+str(timec))
    outputfile.close()

def calresult_time_B(n):
    a,b = read_fileB(n)
    print("The result of group" +str(n) +"in file_B is ")
    start = time.time()
    c,flag=lcs(a,b)
    printLcs(flag,a,len(a),len(b))
    end = time.time()
    timec = end -start
    outputfile = open("../output/time.txt","a")
    outputfile.write("The time of group"+str(n) +"in file_B is "+str(timec)+"\n")
    outputfile.close()



sys.stdout = Logger("../output/result.txt")
for i in range(1,7):
    calresult_time_A(i)
    calresult_time_B(i)