Go – Program to find the length of the longest substring without repeating characters in go golang

In this article, We are going to learn to find the length of the longest substring without repeating characters in go golang.

Example_1:

Input: "abcabcbb"
 
Output: 3

Explanation: Answer is “abc” which has length of 3 

Example_2:

Input: “bbbb”
 
Output: 1
 
Explanation: Answer is “b” which has length of 1 

Example_3:

Input: "pwwkew"
 
Output: 3
 
Explanation : Answer is “wke” which has length of 3
 
Note: Answer must be substring. Here, "pwke" is a subsequence and not a substring. 

Algorithm:

Steps are given below to find the length of the longest substring without repeating characters:

• Get the string as input from user
• Get the length of string
• create an array which will use character ascii value as index number.
• Start searching non-repeating character in a sequence in string. If there is unique character then increment count by 1 and set array index (character ascii value) as true.
• If there is any repeating character then break the loop.
• Compare count with max value. if count is greater than max value. Then assign count value to max variable.

Code:

package main

import (
    "fmt"
)

func lengthOfLongestSubstring(str string) {

    str_len := len(str)

    arr := make([]bool, 125)

    max := 1
    count := 0

    // If string length is zero
    if str_len == 0 {

        max = 0

    } else {
        for i := 0; i < str_len; i++ {

            for j := 0; j < 125; j++ {
                arr[j] = false
            }
            count = 0
            arr[str[i]] = true
            count = 1

            for k := i + 1; k < str_len; k++ {

                if arr[str[k]] {
                    break
                }

               arr[str[k]] = true
               count = count + 1

               if max < count {
                   max = count
               }
               
            }
        }
    }
    fmt.Println(max)
}

func main() {

    var str string

    // Get input string from user
    fmt.Print("Enter string: ")
    fmt.Scan(&str)

    lengthOfLongestSubstring(str)
}

Output:

Enter string: abcabcbb
 3

Enter string: bbbbb
 1

Enter string: pwwkew
 3

To learn more about golang, Please refer given below link:

https://www.techieindoor.com/go-lang-tutorial/

References:

 https://golang.org/doc/
 https://golang.org/pkg/
 https://golang.org/pkg/fmt/
 https://golang.org/pkg/fmt/#Println