字符串反转

#反转字符串
def reverseStr(s):
    if not s:
        return s
    ch = list(s)
    i , j = 0 , len(s)-1
    while i < j:
        ch[i] = chr(ord(ch[i]) ^ ord(ch[j]))
        ch[j] = chr(ord(ch[i]) ^ ord(ch[j]))
        ch[i] = chr(ord(ch[i]) ^ ord(ch[j]))
        # ch[i] = ch[i] ^ ch[j]  【错误的形式】
        # ch[j] = ch[i] ^ ch[j]
        # ch[i] = ch[i] ^ ch[j]
        i += 1
        j -= 1
    return "".join(ch)

s = ‘abcdef‘
print(reverseStr(s))

#反转字符串
def reverseStr(s):
    if not s:
        return s
    ch = list(s)
    i , j = 0 , len(s)-1
    while i < j:
        ch[i] = chr(ord(ch[i]) ^ ord(ch[j]))
        ch[j] = chr(ord(ch[i]) ^ ord(ch[j]))
        ch[i] = chr(ord(ch[i]) ^ ord(ch[j]))
        i += 1
        j -= 1
    return "".join(ch)

#s = ‘abcdef‘
#print(reverseStr(s))

#将句子反转，单词不反转。
def reverseWord(s):
    if not s:
        return s
    rs = reverseStr(s)
    arr = rs.split(‘ ‘)
    res = []
    for a in arr:
        res.append(reverseStr(a))
    return ‘ ‘.join(res)

s = ‘I love dogs‘
print(reverseWord(s))

def rotateWord(words):
    if words == None or len(words) == 0:
        return
    words = list(words[::-1])
    l , r = -1 , -1
    for i in range(len(words)):
        if words[i] != ‘ ‘:
            l = i if (i == 0 or words[i-1] ==‘ ‘) else l
            r = i if (i == len(words)-1 or words[i+1] == ‘ ‘) else r
        if l != -1 and r != -1:
            # reverse(words,l,r)
            words[l:r+1] = words[l:r+1][::-1]
            l , r = -1 , -1
    return ‘‘.join(words)
    
# def reverse(words,l,r):
#     tmp = ‘‘
#     while l<r:
#         tmp = words[l]
#         words[l] = words[r]
#         words[r] = tmp
#         l += 1
#         r -= 1
words = ‘dogs love pigs‘
rotateWord(words)

##将字符串的size大小的左半区移到右边，如size=3，“ABCDE”变成“DEABC”
###三步反转法
def reverseStr(s):
    if not s:
        return s
    ch = list(s)
    i , j = 0, len(s)-1
    while i < j:
        ch[i] = chr(ord(ch[i])^ord(ch[j]))
        ch[j] = chr(ord(ch[i])^ord(ch[j]))
        ch[i] = chr(ord(ch[i])^ord(ch[j]))
        i += 1
        j -= 1
    return "".join(ch)
def reroteStr(s,size):
    if not s:
        return s
    if size > len(s):
        return s
    s = reverseStr(s)
    n = len(s) - size
    left = reverseStr(s[:n])
    right = reverseStr(s[size-1:])
    return left + right

s = ‘ABCDE‘
size = 3
print(reroteStr(s,size))

def sortStr(ss):
    if len(ss)<=1:
        return ss
    s = list(ss)
    i = 0
    j = len(s)-1
    while i != j:
        if s[j].islower():
            s[i] , s[j] = s[j] , s[i]
            i += 1
        elif s[j].isupper():
            j -= 1
    return ‘‘.join(s)
s = ‘aHjDFksn‘
print(sortStr(s))