Given a string, find the maximum number of characters between any two same character in the string. If no character repeats, print -1.
Examples:
Input : str = "abba" Output : 2 The maximum number of characters are between two occurrences of 'a'. Input : str = "baaabcddc" Output : 3 The maximum number of characters are between two occurrences of 'b'. Input : str = "abc" Output : -1
Approach 1 (Simple): Use two nested loops. The outer loop picks character from left to right, the inner loop finds farthest occurrence and keeps track of maximum.
C++
// Simple C++ program to find maximum number // of characters between two occurrences of // same character #include <bits/stdc++.h> using namespace std; int maximumChars(string& str) { int n = str.length(); int res = -1; for (int i = 0; i < n - 1; i++) for (int j = i + 1; j < n; j++) if (str[i] == str[j]) res = max(res, abs(j - i - 1)); return res; } // Driver code int main() { string str = "abba"; cout << maximumChars(str); return 0; } |
Java
// Simple Java program to find maximum // number of characters between two // occurrences of same character class GFG { static int maximumChars(String str) { int n = str.length(); int res = -1; for (int i = 0; i < n - 1; i++) for (int j = i + 1; j < n; j++) if (str.charAt(i) == str.charAt(j)) res = Math.max(res, Math.abs(j - i - 1)); return res; } // Driver code public static void main(String[] args) { String str = "abba"; System.out.println(maximumChars(str)); } } // This code is contributed by vt_m. |
Python3
# Simple Python3 program to find maximum number # of characters between two occurrences of # same character def maximumChars(str): n = len(str) res = -1 for i in range(0, n - 1): for j in range(i + 1, n): if (str[i] == str[j]): res = max(res, abs(j - i - 1)) return res # Driver code if __name__ == '__main__': str = "abba" print(maximumChars(str)) # This code is contributed by PrinciRaj1992 |
C#
// Simple C# program to find maximum // number of characters between two // occurrences of same character using System; public class GFG { static int maximumChars(string str) { int n = str.Length; int res = -1; for (int i = 0; i < n - 1; i++) for (int j = i + 1; j < n; j++) if (str[i] == str[j]) res = Math.Max(res, Math.Abs(j - i - 1)); return res; } // Driver code static public void Main () { string str = "abba"; Console.WriteLine(maximumChars(str)); } } // This code is contributed by vt_m. |
Output:
2
Time Complexity : O(n^2)
Approach 2 (Efficient) : Initialize an array”FIRST” of length 26 in which we have to store first occurrence of an alphabet in the string and another array “LAST” of length 26 in which we will store last occurrence of the alphabet in the string here index 0 is correspond to alphabet a, 1 for b and so on . After that we will take the difference of last and first arrays to find max difference if they are not at same position.
C++
// Efficient C++ program to find maximum number // of characters between two occurrences of // same character #include <bits/stdc++.h> using namespace std; const int MAX_CHAR = 256; int maximumChars(string& str) { int n = str.length(); int res = -1; // Initialize all indexes as -1. int firstInd[MAX_CHAR]; for (int i = 0; i < MAX_CHAR; i++) firstInd[i] = -1; for (int i = 0; i < n; i++) { int first_ind = firstInd[str[i]]; // If this is first occurrence if (first_ind == -1) firstInd[str[i]] = i; // Else find distance from previous // occurrence and update result (if // required). else res = max(res, abs(i - first_ind - 1)); } return res; } // Driver code int main() { string str = "abba"; cout << maximumChars(str); return 0; } |
Java
// Efficient java program to find maximum // number of characters between two // occurrences of same character import java.io.*; public class GFG { static int MAX_CHAR = 256; static int maximumChars(String str) { int n = str.length(); int res = -1; // Initialize all indexes as -1. int []firstInd = new int[MAX_CHAR]; for (int i = 0; i < MAX_CHAR; i++) firstInd[i] = -1; for (int i = 0; i < n; i++) { int first_ind = firstInd[str.charAt(i)]; // If this is first occurrence if (first_ind == -1) firstInd[str.charAt(i)] = i; // Else find distance from previous // occurrence and update result (if // required). else res = Math.max(res, Math.abs(i - first_ind - 1)); } return res; } // Driver code static public void main (String[] args) { String str = "abba"; System.out.println(maximumChars(str)); } } // This code is contributed by vt_m. |
Python3
# Efficient Python3 program to find maximum # number of characters between two occurrences # of same character MAX_CHAR = 256 def maximumChars(str1): n = len(str1) res = -1 # Initialize all indexes as -1. firstInd = [-1 for i in range(MAX_CHAR)] for i in range(n): first_ind = firstInd[ord(str1[i])] # If this is first occurrence if (first_ind == -1): firstInd[ord(str1[i])] = i # Else find distance from previous # occurrence and update result (if # required). else: res = max(res, abs(i - first_ind - 1)) return res # Driver code str1 = "abba"print(maximumChars(str1)) # This code is contributed by Mohit kumar 29 |
C#
// Efficient C# program to find maximum // number of characters between two // occurrences of same character using System; public class GFG { static int MAX_CHAR = 256; static int maximumChars(string str) { int n = str.Length; int res = -1; // Initialize all indexes as -1. int []firstInd = new int[MAX_CHAR]; for (int i = 0; i < MAX_CHAR; i++) firstInd[i] = -1; for (int i = 0; i < n; i++) { int first_ind = firstInd[str[i]]; // If this is first occurrence if (first_ind == -1) firstInd[str[i]] = i; // Else find distance from previous // occurrence and update result (if // required). else res = Math.Max(res, Math.Abs(i - first_ind - 1)); } return res; } // Driver code static public void Main () { string str = "abba"; Console.WriteLine(maximumChars(str)); } } // This code is contributed by vt_m. |
Output:
2
Time Complexity : O(n)
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