Reverse Words in a Given String

Oct 12, 2022 · 1 min read

Question

Given a String S, reverse the string without reversing its individual words. Words are separated by dots.

Example

Input:

S = i.like.this.program.very.much

Output:

much.very.program.this.like.i

Explanation:

After reversing the whole string(not individual words), the input string becomes much.very.program.this.like.i

Algorithm

It’s a really basic problem based upon string & stack. First of all we need to store the words seperated by dots into a stack. Then we need to pop one word after another from the stack and add a dot infront of it in the answer string. Then simply return the string.

Code

#include <bits/stdc++.h>
using namespace std;

class Solution
{
    public:
    //Function to reverse words in a given string.
    string reverseWords(string S) 
    { 
        string curr_str = "";
        stack<string> string_stack;
        for(int i = 0; i < S.length(); i++){
            if(S[i]=='.'){
                string_stack.push(curr_str);
                curr_str = "";
                continue;
            }
            curr_str += S[i];
        }
        //For the last word
        string_stack.push(curr_str);
        
        string newString = "";
        while(!string_stack.empty()){
            newString += string_stack.top();
            string_stack.pop();
            //Because we dont want to add full stop for the last word
            if(!string_stack.empty()){
                newString += '.';
            }
        }
        
        return newString;
    } 
};

//{ Driver Code Starts }.
int main() 
{
    int t;
    cin >> t;
    while (t--) 
    {
        string s;
        cin >> s;
        Solution obj;
        cout<<obj.reverseWords(s)<<endl;
    }
}

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