C#: Find the length of the longest substring without repeating characters from a given string

Last update on December 20 2024 12:44:18 (UTC/GMT +8 hours)

Write a C# Sharp program to find the length of the longest substring without repeating characters in a given string.

Note:
1) Given string consists of English letters, digits, symbols and spaces.
2) 0 <= Given string length <= 5 * 104

Difficulty: Medium.
Company: Amazon, Google, Bloomberg, Microsoft, Adobe, Apple, Oracle, Facebook and more.

Input String : pickoutthelongestsubstring
The longest substring : ubstring
The longest Substring Length : 8

Input String : ppppppppppppp
The longest substring : p
The longest Substring Length : 1

Input String : Microsoft
The longest substring : Micros
The longest Substring Length : 6

Sample Solution:

C# Sharp Code:

using System;
using System.Collections.Generic;

namespace exercises
{
    class Program
    {
        static void Main(string[] args)
        {
            // Define and display original string
            String str1;
            str1 = "aaaaaabbbbccc";
            Console.WriteLine("Original String: " + str1);

            // Calculate and display the length of the longest substring without repeating characters
            Console.WriteLine("Length of the longest substring without repeating characters of the said string:");
            Console.WriteLine(without_repeated_chars_longest_substring(str1));

            // Repeat the process for different strings
            str1 = "BDEFGAABEF";
            Console.WriteLine("Original String: " + str1);
            Console.WriteLine("Length of the longest substring without repeating characters of the said string:");
            Console.WriteLine(without_repeated_chars_longest_substring(str1));

            str1 = "Python";
            Console.WriteLine("Original String: " + str1);
            Console.WriteLine("Length of the longest substring without repeating characters of the said string:");
            Console.WriteLine(without_repeated_chars_longest_substring(str1));

            str1 = "Java";
            Console.WriteLine("Original String: " + str1);
            Console.WriteLine("Length of the longest substring without repeating characters of the said string:");
            Console.WriteLine(without_repeated_chars_longest_substring(str1));
        }

        // Method to find the length of the longest substring without repeating characters
        public static int without_repeated_chars_longest_substring(string str1)
        {
            if (string.IsNullOrEmpty(str1)) return 0;

            // Dictionary to store character positions
            var map_str = new Dictionary<char, int>();
            var max_len = 0;
            var last_repeat_pos = -1;

            // Loop through the string
            for (int i = 0; i < str1.Length; i++)
            {
                // Check if the character exists in the dictionary and update its last position
                if (map_str.ContainsKey(str1[i]) && last_repeat_pos < map_str[str1[i]])
                    last_repeat_pos = map_str[str1[i]];

                // Check for the maximum length of the non-repeating substring
                if (max_len < i - last_repeat_pos)
                    max_len = i - last_repeat_pos;

                // Store current character and its position in the dictionary
                map_str[str1[i]] = i;
            }
            return max_len;
        }
    }
}
;

Sample Output:

Original String: aaaaaabbbbccc
Length of the longest substring without repeating characters of the said string:
2
Original String: BDEFGAABEF
Length of the longest substring without repeating characters of the said string:
6
Original String: Python
Length of the longest substring without repeating characters of the said string:
6
Original String: Java
Length of the longest substring without repeating characters of the said string:
3

Flowchart :

C# Sharp Code Editor:

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