python字符子串_子字符串和子序列（Python）,子串,python

# -*- coding=utf-8 -*-

##### 1: 连续子串最大和 #####

def MaxSum(arr):

res, s = arr[0], arr[0]

for x in arr[1:]:

s = max(x, s+x)

res = max(res, s)

return res

##### 2: 连续子串最大乘积 #####

def MaxMulti(arr):

maxA, minA = [arr[0]], [arr[0]]

res = arr[0]

for i in range(1, len(arr)):

maxA.append(max(arr[i], maxA[i-1]*arr[i], minA[i-1]*arr[i]))

minA.append(min(arr[i], maxA[i-1]*arr[i], minA[i-1]*arr[i]))

res = max(res, maxA[-1])

return res

#### 3：最长递增子序列 ####

def LIS(arr):

dp = [1] * len(arr)

for i in range(len(arr)):

temp = 1

for j in range(i-1, -1, -1):

if arr[i] > arr[j]:

temp = max(temp, dp[j]+1)

dp[i] = temp

return max(dp)

#### 4：最长公共子串 ####

def LongSubStr(s1,s2):

dp = [[0] * (len(s2)+1) for _ in range(len(s1)+1)]

res = 0

for i in range(1, len(s1)+1):

for j in range(1, len(s2)+1):

if s1[i-1] == s2[j-1]:

dp[i][j] = dp[i-1][j-1] + 1

res = max(res, max(dp[i]))

return res

#### 5：最长公共子序列 ####

def LongSubSeq(s1,s2):

dp = [[0] * (len(s2)+1) for _ in range(len(s1)+1)]

res = 0

for i in range(1, len(s1)+1):

for j in range(1, len(s2)+1):

if s1[i-1] == s2[j-1]:

dp[i][j] = dp[i-1][j-1] + 1

else:

dp[i][j] = max(dp[i][j-1], dp[i-1][j])

res = max(res, max(dp[i]))

return res

#### 6：最长回文子串 ####

def LongPalindrome(s):

dp = [[False]*len(s) for _ in range(len(s))]

res = ''

for x in range(len(s)):

for i in range(len(s)-x):

j = i + x

if x == 0:

dp[i][j] = True

elif x == 1:

dp[i][j] = (s[i] == s[j])

else:

dp[i][j] = (s[i] == s[j] and dp[i+1][j-1])

if dp[i][j] and j-i+1 > len(res):

res = s[i:j+1]

return res

#### 7：最长回文子序列 ####

def LongPalindromeSubseq(s):

dp = [[0] * len(s) for _ in range(len(s))]

for i in range(len(s)-1, -1, -1):

dp[i][i] = 1

for j in range(i+1, len(s)):

if s[i] == s[j]:

dp[i][j] = dp[i+1][j-1] + 2

else:

dp[i][j] = max(dp[i+1][j], dp[i][j-1])

return dp[0][-1]

num = [1,3,4,0,6,5,-1,2]

s1 = 'ASDSVAFA'

s2 = 'ABDSVSDF'

print(MaxSum(num), MaxMulti(num), LIS(num))

print(LongSubStr(s1, s2), LongSubSeq(s1,s2))

print(LongPalindrome(s1), LongPalindromeSubseq(s1))