Delete consecutive same words in a sequence

Given a sequence of n strings, the task is to check if any two similar words come together then they destroy each other then print the number of words left in the sequence after this pairwise destruction.

Examples:

Input : ab aa aa bcd ab
Output : 3
As aa, aa destroys each other so, ab bcd ab is the
new sequence.

Input :  tom jerry jerry tom
Output : 0
As first both jerry will destroy each other.
Then sequence will be tom, tom they will also destroy
each other. So, the final sequence doesn't contain any
word.

Recommended: Please solve it on “PRACTICE” first, before moving on to the solution.

Method 1:

1- Start traversing the sequence by storing it in vector.
  a) Check if the current string is equal to next string
     if yes, erase both from the vector.
  b) And check the same till last.
2- Return vector size.

C++

// C++ program to remove consecutive same words 
#include<bits/stdc++.h> 
using namespace std; 
  
// Function to find the size of manipulated sequence 
int removeConsecutiveSame(vector <string > v) 
{ 
    int n = v.size(); 
  
    // Start traversing the sequence 
    for (int i=0; i<n-1; ) 
    { 
        // Compare the current string with next one 
        // Erase both if equal 
        if (v[i].compare(v[i+1]) == 0) 
        { 
            // Erase function delete the element and 
            // also shifts other element that's why 
            // i is not updated 
            v.erase(v.begin()+i); 
            v.erase(v.begin()+i); 
  
            // Update i, as to check from previous 
            // element again 
            if (i > 0) 
                i--; 
  
            // Reduce sequence size 
            n = n-2; 
        } 
  
        // Increment i, if not equal 
        else
            i++; 
    } 
  
    // Return modified size 
    return v.size(); 
} 
  
// Driver code 
int main() 
{ 
    vector<string> v = { "tom", "jerry", "jerry", "tom"}; 
    cout << removeConsecutiveSame(v); 
    return 0; 
} 

Java

// Java program to remove consecutive same words 
  
import java.util.Vector; 
  
class Test 
{ 
    // Method to find the size of manipulated sequence 
    static int removeConsecutiveSame(Vector <String > v) 
    { 
        int n = v.size(); 
       
        // Start traversing the sequence 
        for (int i=0; i<n-1; ) 
        { 
            // Compare the current string with next one 
            // Erase both if equal 
            if (v.get(i).equals(v.get(i+1))) 
            { 
                // Erase function delete the element and 
                // also shifts other element that's why 
                // i is not updated 
                v.remove(i); 
                v.remove(i); 
       
                // Update i, as to check from previous 
                // element again 
                if (i > 0) 
                    i--; 
       
                // Reduce sequence size 
                n = n-2; 
            } 
       
            // Increment i, if not equal 
            else
                i++; 
        } 
       
        // Return modified size 
        return v.size(); 
    } 
      
    // Driver method 
    public static void main(String[] args)  
    { 
        Vector<String> v = new Vector<>(); 
  
        v.addElement("tom"); v.addElement("jerry"); 
        v.addElement("jerry");v.addElement("tom"); 
  
        System.out.println(removeConsecutiveSame(v)); 
    } 
} 

Python3

# Python3 program to remove consecutive  
# same words  
  
# Function to find the size of  
# manipulated sequence  
def removeConsecutiveSame(v): 
  
    n = len(v) 
  
    # Start traversing the sequence 
    i = 0
    while(i < n - 1): 
          
        # Compare the current string with  
        # next one Erase both if equal  
        if ((i + 1) < len(v)) and (v[i] == v[i + 1]):  
          
            # Erase function delete the element and  
            # also shifts other element that's why  
            # i is not updated  
            v = v[:i]  
            v = v[:i]  
  
            # Update i, as to check from previous  
            # element again  
            if (i > 0): 
                i -= 1
  
            # Reduce sequence size  
            n = n - 2
          
        # Increment i, if not equal  
        else: 
            i += 1
      
    # Return modified size  
    return len(v[:i - 1]) 
      
# Driver Code 
if __name__ == '__main__': 
    v = ["tom", "jerry", "jerry", "tom"] 
    print(removeConsecutiveSame(v)) 
      
# This code is contributed by SHUBHAMSINGH10 

C#

// C# program to remove consecutive same words  
using System; 
using System.Collections.Generic; 
  
class GFG 
{ 
// Method to find the size of  
// manipulated sequence  
public static int removeConsecutiveSame(List<string> v) 
{ 
    int n = v.Count; 
  
    // Start traversing the sequence  
    for (int i = 0; i < n - 1;) 
    { 
        // Compare the current string with  
        // next one Erase both if equal  
        if (v[i].Equals(v[i + 1])) 
        { 
            // Erase function delete the element and  
            // also shifts other element that's why  
            // i is not updated  
            v.RemoveAt(i); 
            v.RemoveAt(i); 
  
            // Update i, as to check from  
            // previous element again  
            if (i > 0) 
            { 
                i--; 
            } 
  
            // Reduce sequence size  
            n = n - 2; 
        } 
  
        // Increment i, if not equal  
        else
        { 
            i++; 
        } 
    } 
  
    // Return modified size  
    return v.Count; 
} 
  
// Driver Code  
public static void Main(string[] args) 
{ 
    List<string> v = new List<string>(); 
  
    v.Add("tom"); 
    v.Add("jerry"); 
    v.Add("jerry"); 
    v.Add("tom"); 
  
    Console.WriteLine(removeConsecutiveSame(v)); 
} 
} 
  
// This code is contributed by Shrikant13 

Output:

Method 2:(Using Stack)

1- Start traversing the strings and push into stack.
    a) Check if the current string is same as the string
       at the top of the stack
        i) If yes, pop the string from top.
        ii) Else push the current string.
2- Return stack size if the whole sequence is traversed.

C++

//  C++ implementation of above method 
#include<bits/stdc++.h> 
using namespace std; 
  
// Function to find the size of manipulated sequence 
int removeConsecutiveSame(vector <string> v) 
{ 
    stack<string> st; 
  
    // Start traversing the sequence 
    for (int i=0; i<v.size(); i++) 
    { 
        // Push the current string if the stack 
        // is empty 
        if (st.empty()) 
            st.push(v[i]); 
        else
        { 
            string str = st.top(); 
  
            // compare the current string with stack top 
            // if equal, pop the top 
            if (str.compare(v[i]) == 0) 
                st.pop(); 
  
            // Otherwise push the current string 
            else
                st.push(v[i]); 
        } 
    } 
  
    // Return stack size 
    return st.size(); 
} 
  
// Driver code 
int main() 
{ 
    vector<string> V = { "ab", "aa", "aa", "bcd", "ab"}; 
    cout << removeConsecutiveSame(V); 
    return 0; 
} 

Java

//  Java implementation of above method 
  
import java.util.Stack; 
import java.util.Vector; 
  
class Test 
{ 
    // Method to find the size of manipulated sequence 
    static int removeConsecutiveSame(Vector <String> v) 
    { 
        Stack<String> st = new Stack<>(); 
       
        // Start traversing the sequence 
        for (int i=0; i<v.size(); i++) 
        { 
            // Push the current string if the stack 
            // is empty 
            if (st.empty()) 
                st.push(v.get(i)); 
            else
            { 
                String str = st.peek(); 
       
                // compare the current string with stack top 
                // if equal, pop the top 
                if (str.equals(v.get(i)))     
                    st.pop(); 
       
                // Otherwise push the current string 
                else
                    st.push(v.get(i)); 
            } 
        } 
       
        // Return stack size 
        return st.size(); 
    } 
      
    // Driver method 
    public static void main(String[] args)  
    { 
        Vector<String> v = new Vector<>(); 
          
        v.addElement("ab"); v.addElement("aa"); 
        v.addElement("aa");v.addElement("bcd"); 
        v.addElement("ab"); 
          
        System.out.println(removeConsecutiveSame(v)); 
    } 
} 

Python3

# Python implementation of above method  
  
# Function to find the size of manipulated sequence  
def removeConsecutiveSame(v): 
    st = [] 
  
    # Start traversing the sequence 
    for i in range(len(v)): 
          
        # Push the current string if the stack  
        # is empty  
        if (len(st) == 0):  
            st.append(v[i])  
        else: 
            Str = st[-1]  
  
            # compare the current string with stack top  
            # if equal, pop the top  
            if (Str == v[i]):  
                st.pop()  
  
            # Otherwise push the current string  
            else: 
                st.append(v[i]) 
  
    # Return stack size  
    return len(st) 
  
# Driver code  
if __name__ == '__main__': 
    V = [ "ab", "aa", "aa", "bcd", "ab"]  
    print(removeConsecutiveSame(V)) 
  
# This code is contributed by PranchalK. 

C#

// C# implementation of above method  
using System; 
using System.Collections.Generic; 
  
class GFG 
{ 
// Method to find the size of  
// manipulated sequence  
public static int removeConsecutiveSame(List<string> v) 
{ 
    Stack<string> st = new Stack<string>(); 
  
    // Start traversing the sequence  
    for (int i = 0; i < v.Count; i++) 
    { 
        // Push the current string if  
        // the stack is empty  
        if (st.Count == 0) 
        { 
            st.Push(v[i]); 
        } 
        else
        { 
            string str = st.Peek(); 
  
            // compare the current string with   
            // stack top if equal, pop the top  
            if (str.Equals(v[i])) 
            { 
                st.Pop(); 
            } 
  
            // Otherwise push the current  
            // string  
            else
            { 
                st.Push(v[i]); 
            } 
        } 
    } 
  
    // Return stack size  
    return st.Count; 
} 
  
// Driver Code  
public static void Main(string[] args) 
{ 
    List<string> v = new List<string>(); 
  
    v.Add("ab"); 
    v.Add("aa"); 
    v.Add("aa"); 
    v.Add("bcd"); 
    v.Add("ab"); 
  
    Console.WriteLine(removeConsecutiveSame(v)); 
} 
} 
  
// This code is contributed by Shrikant13 

Output:

This article is contributed by Sahil Chhabra. If you like GeeksforGeeks and would like to contribute, you can also write an article using contribute.geeksforgeeks.org or mail your article to contribute@geeksforgeeks.org. See your article appearing on the GeeksforGeeks main page and help other Geeks.

Please write comments if you find anything incorrect, or you want to share more information about the topic discussed above.

GeeksforGeeks has prepared a complete interview preparation course with premium videos, theory, practice problems, TA support and many more features. Please refer Placement 100 for details

My Personal Notes

Recommended: Please solve it on “PRACTICE” first, before moving on to the solution.

C++

Java

Python3

C#

C++

Java

Python3

C#

Recommended Posts: