Check If every group of a’s is followed by a group of b’s of same length

Given a string str, the task is to check whether every group of consecutive a’s is followed by a group of consecutive b’s of same length. If the condition is true for every group then print 1 else print 0.

Examples:

Input: str = “ababaabb”
Output: 1
ab, ab, aabb. All groups are valid

Input: str = “aabbabb”
Output: 0
aabb, abb (A single ‘a’ followed by 2 ‘b’)



Approach:

  • For every a in the string increment the count.
  • Starting from the first b, decrement the count for every b.
  • If at the end of the above cycle, count != 0 then return false.
  • Else repeat the first two steps for the rest of the string.
  • Return true if the condition is satisfied for all the cycles else print 0.

Below is the implementation of the above approach:

C++

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// C++ implementation of the approach
#include <bits/stdc++.h>
using namespace std;
  
// Function to match whether there are always n consecutive b's
// followed by n consecutive a's throughout the string
int matchPattern(string s)
{
    int count = 0;
    int n = s.length();
  
    // Traverse through the string
    int i = 0;
    while (i < n) {
  
        // Count a's in current segment
        while (i < n && s[i] == 'a') {
            count++;
            i++;
        }
  
        // Count b's in current segment
        while (i < n && s[i] == 'b') {
            count--;
            i++;
        }
  
        // If both counts are not same.
        if (count != 0)
            return false;
    }
  
    return true;
}
  
// Driver code
int main()
{
    string s = "bb";
    if (matchPattern(s) == true)
        cout << "Yes";
    else
        cout << "No";
    return 0;
}

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Java

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// Java implementation of the above approach
  
public class GFG{
  
// Function to match whether there are always n consecutive b's
// followed by n consecutive a's throughout the string
static boolean matchPattern(String s)
{
    int count = 0;
    int n = s.length();
  
    // Traverse through the string
    int i = 0;
    while (i < n) {
  
        // Count a's in current segment
        while (i < n && s.charAt(i) == 'a') {
            count++;
            i++;
        }
  
        // Count b's in current segment
        while (i < n && s.charAt(i) == 'b') {
            count--;
            i++;
        }
  
        // If both counts are not same.
        if (count != 0)
            return false;
    }
  
    return true;
}
  
// Driver code
public static void main(String []args)
{
    String s = "bb";
    if (matchPattern(s) == true)
        System.out.println("Yes");
    else
        System.out.println("No");
}
  
// This code is contributed by Ryuga
}

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C#

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// C# implementation of the above approach
   
using System;
public class GFG{
   
// Function to match whether there are always n consecutive b's
// followed by n consecutive a's throughout the string
static bool matchPattern(string s)
{
    int count = 0;
    int n = s.Length;
   
    // Traverse through the string
    int i = 0;
    while (i < n) {
   
        // Count a's in current segment
        while (i < n && s[i] == 'a') {
            count++;
            i++;
        }
   
        // Count b's in current segment
        while (i < n && s[i] == 'b') {
            count--;
            i++;
        }
   
        // If both counts are not same.
        if (count != 0)
            return false;
    }
   
    return true;
}
   
// Driver code
public static void Main()
{
    string s = "bb";
    if (matchPattern(s) == true)
        Console.Write("Yes");
    else
        Console.Write("No");
}
  
}

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Output:

No


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Improved By : Ryuga