{"id":26906,"date":"2017-12-26T21:14:28","date_gmt":"2017-12-26T15:44:28","guid":{"rendered":"https:\/\/www.wikitechy.com\/technology\/?p=26906"},"modified":"2017-12-26T21:14:28","modified_gmt":"2017-12-26T15:44:28","slug":"python-algorithm-reverse-string-using-stack","status":"publish","type":"post","link":"https:\/\/www.wikitechy.com\/technology\/python-algorithm-reverse-string-using-stack\/","title":{"rendered":"Python Algorithm – Reverse a String using Stack"},"content":{"rendered":"

Given a string, reverse it using stack. For example \u201cGeeksQuiz\u201d should be converted to \u201cziuQskeeG\u201d.<\/p>\n

Following is simple algorithm to reverse a string using stack.<\/p>\n

1) Create an empty stack.\r\n2) One by one push all characters of string to stack.\r\n3) One by one pop all characters from stack and put \r\n   them back to string.<\/pre>\n
Following are C and Python programs that implements above algorithm.<\/p>\n
Python \u00a0Programming:<\/strong><\/p>\n
 
 <\/div> 
# Python program to reverse a string using stack # Function to create an empty stack. It initializes size of stack as 0def createStack():    stack=[]    return stack # Function to determine the size of the stackdef size(stack):    return len(stack) # Stack is empty if the size is 0def isEmpty(stack):    if size(stack) == 0:        return true # Function to add an item to stack . It increases size by 1    def push(stack,item):    stack.append(item) #Function to remove an item from stack. It decreases size by 1def pop(stack):    if isEmpty(stack): return    return stack.pop() # A stack based function to reverse a stringdef reverse(string):    n = len(string)         # Create a empty stack    stack = createStack()     # Push all characters of string to stack    for i in range(0,n,1):        push(stack,string[i])     # Making the string empty since all characters are saved in stack        string=""     # Pop all characters of string and put them back to string    for i in range(0,n,1):        string+=pop(stack)             return string     # Driver program to test above functionsstring="GeeksQuiz"string = reverse(string)print("Reversed string is " + string) # This code is contributed by Sunny Karira<\/code><\/pre> <\/div>\n
Output:<\/strong><\/p>\n
Reversed string is ziuQskeeG<\/pre>\n

\nTime Complexity: <\/strong>O(n) where n is number of characters in stack.
\nAuxiliary Space: <\/strong>O(n) for stack.<\/p>\n[ad type=”banner”]\n
A string can also be reversed without using any auxiliary space. Following C and Python programs to implement reverse without using stack.<\/p>\n
Python Programming:<\/strong><\/p>\n
 
 <\/div> 
# Python program to reverse a string without stack # Function to reverse a stringdef reverse(string):    string = string[::-1]    return string # Driver program to test above functionsstring = "abc"string = reverse(string)print("Reversed string is " + string) # This code is contributed by Sunny Karira<\/code><\/pre> <\/div>\n
Output:<\/strong><\/p>\n
Reversed string is cba<\/pre>\n[ad type=”banner”]\n","protected":false},"excerpt":{"rendered":"
Python Algorithm – Evaluation of Postfix Expression – Data Structure – Given a string, reverse it using stack. For example \u201cGeeksQuiz\u201d should be converted <\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[69969,79607],"tags":[80281,80219,80283,80284,80134,80135,80216,80133,80282,80217],"class_list":["post-26906","post","type-post","status-publish","format-standard","hentry","category-algorithm","category-stack","tag-algorithm-to-reverse-a-string-using-stack-in-data-structure","tag-c-program-using-stack-to-display-reverse-of-the-string","tag-data-structure-to-reverse-string","tag-data-structure-to-reverse-string-without-stack","tag-reverse-a-number-using-stack-in-c","tag-reverse-a-stack-using-recursion-in-c","tag-reverse-a-string-using-stack-in-java","tag-reverse-a-string-using-stack-in-python","tag-write-a-simple-program-to-reverse-a-string-using-a-stack","tag-write-an-algorithm-to-reverse-an-input-string-of-characters-using-a-stack"],"_links":{"self":[{"href":"https:\/\/www.wikitechy.com\/technology\/wp-json\/wp\/v2\/posts\/26906","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.wikitechy.com\/technology\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.wikitechy.com\/technology\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.wikitechy.com\/technology\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.wikitechy.com\/technology\/wp-json\/wp\/v2\/comments?post=26906"}],"version-history":[{"count":0,"href":"https:\/\/www.wikitechy.com\/technology\/wp-json\/wp\/v2\/posts\/26906\/revisions"}],"wp:attachment":[{"href":"https:\/\/www.wikitechy.com\/technology\/wp-json\/wp\/v2\/media?parent=26906"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.wikitechy.com\/technology\/wp-json\/wp\/v2\/categories?post=26906"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.wikitechy.com\/technology\/wp-json\/wp\/v2\/tags?post=26906"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}