Given a string of lowercase, find the length of the longest substring that does not contain any palindrome as a substring.
Examples:
Input : str = "daiict" Output : 3 dai, ict are longest substring that do not contain any palindrome as substring Input : str = "a" Output : 0 a is itself a palindrome
The idea is to observe that if any character forms a palindrome, it can not be included in any substring. So, in that case, the required substring will be picked from before or after that character which forms a palindrome.Â
Therefore, a simple solution is to traverse the string and, for each character, check whether it forms a palindrome of length 2 or 3 with its adjacent characters. If it does not, then increase the length of the substring, otherwise re-initialize the length of the substring to zero. Using this approach, find the length of the maximum substring.
Below is the implementation of the above approach:
C++
// C++ implementation of the above approachÂ
#include <bits/stdc++.h>using namespace std;Â
// Function to find the length of the longest// substringint lenoflongestnonpalindrome(string s){    // initializing the variables    int max1 = 1, len = 0;Â
    for (int i = 0; i < s.length() - 1; i++) {        // checking palindrome of size 2        // example: aa        if (s[i] == s[i + 1])            len = 0;        // checking palindrome of size 3        // example: aba        else if (s[i + 1] == s[i - 1] && i > 0)            len = 1;        else // incrementing length of substring            len++;        max1 = max(max1, len + 1); // finding maximum    }Â
    // if there exists single character then    // it is always palindrome    if (max1 == 1)        return 0;    else        return max1;}Â
// Driver Codeint main(){Â Â Â Â string s = "synapse";Â Â Â Â cout << lenoflongestnonpalindrome(s) << "\n";Â Â Â Â return 0;} |
Java
// Java implementation of the above approachimport java.util.Arrays;import java.lang.Math;Â
class GFG {Â
    // Function to find the length of the longest    // substring    public static int lenoflongestnonpalindrome(String s)    {        // initializing the variables        int max1 = 1, len = 0;        char[] new_str = s.toCharArray();Â
        for (int i = 0; i < new_str.length - 1; i++) {            // checking palindrome of size 2            // example: aa            if (new_str[i] == new_str[i + 1])                len = 0;            // checking palindrome of size 3            // example: aba            else if (i > 0 && (new_str[i + 1] == new_str[i - 1]))                len = 1;            else // incrementing length of substring                len++;            max1 = Math.max(max1, len + 1); // finding maximum        }Â
        // if there exits single character then        // it is always palindrome        if (max1 == 1)            return 0;        else            return max1;    }Â
    // Driver Code    public static void main(String[] args)    {        String s = "synapse";        System.out.println(lenoflongestnonpalindrome(s));    }}Â
// This code is contributed by princiraj1992 |
Python3
# Python3 implementation of the above approach Â
# Function to find the length # of the longest substring def lenoflongestnonpalindrome(s): Â
    # initializing the variables     max1, length = 1, 0Â
    for i in range(0, len(s) - 1):                  # checking palindrome of         # size 2 example: aa         if s[i] == s[i + 1]:             length = 0                     # checking palindrome of         # size 3 example: aba         elif s[i + 1] == s[i - 1] and i > 0:            length = 1        else: # incrementing length of substring             length += 1        max1 = max(max1, length + 1) # finding maximum Â
    # If there exits single character     # then it is always palindrome     if max1 == 1:         return 0    else:        return max1 Â
# Driver Code if __name__ == "__main__":Â
    s = "synapse"    print(lenoflongestnonpalindrome(s))     # This code is contributed by Rituraj Jain |
C#
// C# implementation of the above approach using System;Â Â Â Â Â class GFG {Â
    // Function to find the length of the longest    // substring    public static int lenoflongestnonpalindrome(String s)    {        // initializing the variables        int max1 = 1, len = 0;        char[] new_str = s.ToCharArray();Â
        for (int i = 0; i < new_str.Length - 1; i++)         {            // checking palindrome of size 2            // example: aa            if (new_str[i] == new_str[i + 1])                len = 0;                             // checking palindrome of size 3            // example: aba            else if (i > 0 && (new_str[i + 1] == new_str[i - 1]))                len = 1;            else // incrementing length of substring                len++;            max1 = Math.Max(max1, len + 1); // finding maximum        }Â
        // if there exits single character then        // it is always palindrome        if (max1 == 1)            return 0;        else            return max1;    }Â
    // Driver Code    public static void Main(String[] args)    {        String s = "synapse";        Console.WriteLine(lenoflongestnonpalindrome(s));    }}Â
// This code has been contributed by 29AjayKumar |
PHP
<?php// PHP implementation of the above approach Â
// Function to find the length of the longest // substring function lenoflongestnonpalindrome($s) {     // initializing the variables     $max1 = 1; $len = 0; Â
    for ($i = 0; $i < strlen($s) - 1; $i++)     {         // checking palindrome of size 2         // example: aa         if ($s[$i] == $s[$i + 1])             $len = 0;                      // checking palindrome of size 3         // example: aba         else if ($s[$i + 1] == $s[$i - 1] && $i > 0)             $len = 1;         else // incrementing length of substring             $len++;         $max1 = max($max1, $len + 1); // finding maximum     } Â
    // if there exits single character then     // it is always palindrome     if ($max1 == 1)         return 0;     else        return $max1; } Â
// Driver Code $s = "synapse"; echo lenoflongestnonpalindrome($s), "\n"; Â
// This code is contributed by AnkitRai01Â
?> |
Javascript
<script>Â
// JavaScript implementation of the above approachÂ
// Function to find the length of the longest// substringfunction lenoflongestnonpalindrome(s){    // initializing the variables    let max1 = 1, len = 0;Â
    for (let i = 0; i < s.length - 1; i++) {        // checking palindrome of size 2        // example: aa        if (s[i] == s[i + 1])            len = 0;        // checking palindrome of size 3        // example: aba        else if (s[i + 1] == s[i - 1] && i > 0)            len = 1;        else // incrementing length of substring            len++;        max1 = Math.max(max1, len + 1); // finding maximum    }Â
    // if there exits single character then    // it is always palindrome    if (max1 == 1)        return 0;    else        return max1;}Â
// Driver CodeÂ
    let s = "synapse";    document.write(lenoflongestnonpalindrome(s) + "<br>");     Â
//This code is contributed by Manoj</script> |
Output:Â
7
Â
Time complexity: O(n) where n is length of input string
Auxiliary Space: O(1)
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