Python程序检查字符串是对称的还是回文的

给定一个字符串。任务是检查字符串是否对称和回文。如果字符串的两半相同，则称该字符串是对称的；如果字符串的一半与另一半相反，或者如果字符串在向前读取时看起来相同，则称该字符串为回文字符串。落后。

例子：

Input: khokho
Output: 
The entered string is symmetrical
The entered string is not palindrome

Input:amaama
Output:
The entered string is symmetrical
The entered string is palindrome

方法1：方法非常幼稚。在回文的情况下，循环运行到字符串的中间，并且匹配第一个和最后一个字符。如果字符不相似，则循环中断并且字符串不是回文，否则字符串是回文。在对称的情况下，如果字符串长度是偶数，则将字符串分成两半并运行循环，检查两半字符串的字符。如果字符不相似，则循环中断并且字符串不对称，否则字符串是对称的。如果字符串长度是奇数，则将字符串分成两半，使中间元素不被选中，并重复上述相同步骤。

下面是实现。

Python3

# Python program to demonstrate
# symmetry and palindrome of the
# string
 
 
# Function to check whether the
# string is palindrome or not
def palindrome(a):
  
    # finding the mid, start
    # and last index of the string
    mid = (len(a)-1)//2     #you can remove the -1 or you add <= sign in line 21 
    start = 0                #so that you can compare the middle elements also.
    last = len(a)-1
    flag = 0
 
    # A loop till the mid of the
    # string
    while(start <= mid):
  
        # comparing letters from right
        # from the letters from left
        if (a[start]== a[last]):
             
            start += 1
            last -= 1
             
        else:
            flag = 1
            break;
             
    # Checking the flag variable to
    # check if the string is palindrome
    # or not
    if flag == 0:
        print("The entered string is palindrome")
    else:
        print("The entered string is not palindrome")
         
# Function to check whether the
# string is symmetrical or not       
def symmetry(a):
     
    n = len(a)
    flag = 0
     
    # Check if the string's length
    # is odd or even
    if n%2:
        mid = n//2 +1
    else:
        mid = n//2
         
    start1 = 0
    start2 = mid
     
    while(start1 < mid and start2 < n):
         
        if (a[start1]== a[start2]):
            start1 = start1 + 1
            start2 = start2 + 1
        else:
            flag = 1
            break
      
    # Checking the flag variable to
    # check if the string is symmetrical
    # or not
    if flag == 0:
        print("The entered string is symmetrical")
    else:
        print("The entered string is not symmetrical")
         
# Driver code
string = 'amaama'
palindrome(string)
symmetry(string)

输出

The entered string is palindrome
The entered string is symmetrical

方法二：

我们在这种方法中使用切片。

Python3

string = 'amaama'
half = int(len(string) / 2)
 
if len(string) % 2 == 0:  # even
    first_str = string[:half]
    second_str = string[half:]
else:  # odd
    first_str = string[:half]
    second_str = string[half+1:]
 
# symmetric
if first_str == second_str:
    print(string, 'string is symmertical')
else:
    print(string, 'string is not symmertical')
 
# palindrome
if first_str == second_str[::-1]:  # ''.join(reversed(second_str)) [slower]
    print(string, 'string is palindrome')
else:
    print(string, 'string is not palindrome')

输出

amaama string is symmertical
amaama string is palindrome