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Check if the given string is linear or not
  • Difficulty Level : Easy
  • Last Updated : 11 May, 2021

Given string str, the task is to check whether the given string is linear or not. If it is linear then print “Yes” else print “No”.  

Let the string be “abcdefghij”. It can be broken as: 
“a” 
“bc” 
“def” 
“ghij” 
if the character a, b, c, and are equal then the given string is linear otherwise not. 
Therefore if the string is of the form “xxaxabcxabcdxabcdexab…” then it is called as the linear string.  

Examples:  

Input: str = “aapaxyayziabcde” 
Output: Yes 
Explanation: 

ap 
axy 
ayzi 
abcde 
All the broken string have same character as the first character.
Input: str = “bbobfycd” 
Output: No 
Explanation: 

bo 
bfy 
cd 
Here b=b=b!=c  

Approach: To check if the given string is of the form “xxaxabcxabcdxabcdexab…” then we have to check if characters at index 0, 1, 3, 6, 10, … are equals or not. 
If all the characters at the above indexes are equal then the given string is Linear String otherwise it is not.



Below is the implementation of the above approach: 

C++




// C++ program for the above approach
#include <bits/stdc++.h>
using namespace std;
 
// Function to check if the given
// string is linear or not
int is_linear(string s)
{
    int tmp = 0;
 
    char first = s[0];
 
    // Iterate over string
    for (int pos = 0; pos < s.length();
        pos += tmp) {
 
        // If character is not same as
        // the first character then
        // return false
        if (s[pos] != first) {
            return false;
        }
 
        // Increment the tmp
        tmp++;
    }
 
    return true;
}
 
// Driver Code
int main()
{
    // Given String str
    string str = "aapaxyayziabcde";
 
    // Function Call
    if (is_linear(str)) {
        cout << "Yes" << endl;
    }
    else {
        cout << "No" << endl;
    }
 
    return 0;
}

Java




// Java program for the above approach
import java.util.*;
   
class GFG{
  
// Function to check if the given
// string is linear or not
static boolean is_linear(String s)
{
    int tmp = 0;
    char first = s.charAt(0);
  
    // Iterate over string
    for(int pos = 0; pos < s.length();
            pos += tmp)
    {
         
        // If character is not same as
        // the first character then
        // return false
        if (s.charAt(pos) != first)
        {
            return false;
        }
         
        // Increment the tmp
        tmp++;
    }
    return true;
}
 
// Driver code
public static void main(String[] args)
{
     
    // Given String str
    String str = "aapaxyayziabcde";
 
    // Function call
    if (is_linear(str))
    {
        System.out.println("Yes");
    }
    else
    {
        System.out.println("No");
    }
}
}
 
// This code is contributed by offbeat

Python3




# Python3 program for the above approach
 
# Function to check if the given
# is linear or not
def is_linear(s):
 
    tmp = 0
    first = s[0]
    pos = 0
     
    # Iterate over string
    while pos < len(s):
 
        # If character is not same as
        # the first character then
        # return false
        if (s[pos] != first):
            return False
         
        # Increment the tmp
        tmp += 1
        pos += tmp
         
    return True
 
# Driver Code
if __name__ == '__main__':
 
    # Given String str
    str = "aapaxyayziabcde"
 
    # Function call
    if (is_linear(str)):
        print("Yes")
    else:
        print("No")
 
# This code is contributed by mohit kumar 29

C#




// C# program for the above approach
using System;
  
class GFG{
     
// Function to check if the given
// string is linear or not
static bool is_linear(String s)
{
    int tmp = 0;
    char first = s[0];
 
    // Iterate over string
    for(int pos = 0; pos < s.Length;
            pos += tmp)
    {
         
        // If character is not same as
        // the first character then
        // return false
        if (s[pos] != first)
        {
            return false;
        }
 
        // Increment the tmp
        tmp++;
    }
    return true;
}
 
// Driver code
public static void Main(String[] args)
{
     
    // Given String str
    String str = "aapaxyayziabcde";
 
    // Function call
    if (is_linear(str))
    {
        Console.Write("Yes");
    }
    else
    {
        Console.Write("No");
    }
}
}
 
// This code is contributed by grand_master

Javascript




<script>
 
// Javascript program for the above approach
 
// Function to check if the given
// string is linear or not
function is_linear(s)
{
    let tmp = 0;
    let first = s[0];
    
    // Iterate over string
    for(let pos = 0; pos < s.length;
            pos += tmp)
    {
           
        // If character is not same as
        // the first character then
        // return false
        if (s[pos] != first)
        {
            return false;
        }
           
        // Increment the tmp
        tmp++;
    }
    return true;
}
  
 
// Driver Code
 
    // Given String str
    let str = "aapaxyayziabcde";
   
    // Function call
    if (is_linear(str))
    {
        document.write("Yes");
    }
    else
    {
        document.write("No");
    }
 
</script>
Output: 
Yes

 

Time Complexity: O(log N) 
Auxiliary Space: O(1)
 

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