How to resolve the algorithm Range extraction step by step in the Go programming language

Published on 12 May 2024 09:40 PM
#Go

How to resolve the algorithm Range extraction step by step in the Go programming language

Table of Contents

Problem Statement

A format for expressing an ordered list of integers is to use a comma separated list of either Example The list of integers: Is accurately expressed by the range expression: (And vice-versa).

Let's start with the solution:

Step by Step solution about How to resolve the algorithm Range extraction step by step in the Go programming language

This Go program takes an array of integers and converts it into a range format, which is a string that represents a range of numbers, such as "1-5" or "10,12,14".

The main function calls the rangeFormat function, passing in a slice of integers, and prints the result.

The rangeFormat function takes an array of integers as input and returns a string with the range format, or an error if the input is invalid.

The function first checks if the input array is empty. If it is, it returns an empty string and nil.

Next, it creates a slice of strings to store the parts of the range format.

Then, it enters a loop that iterates over the input array, looking for ranges of consecutive numbers. If it finds a range, it adds a string representing that range to the parts slice.

The loop continues until it has processed all of the elements in the input array.

After the loop, the function joins the parts of the range format together with commas and returns the result.

If the input array contains any invalid values (e.g., non-consecutive numbers or repeated values), the function returns an error instead.

Source code in the go programming language

package main

import (
    "errors"
    "fmt"
    "strconv"
    "strings"
)

func main() {
    rf, err := rangeFormat([]int{
        0, 1, 2, 4, 6, 7, 8, 11, 12, 14,
        15, 16, 17, 18, 19, 20, 21, 22, 23, 24,
        25, 27, 28, 29, 30, 31, 32, 33, 35, 36,
        37, 38, 39,
    })
    if err != nil {
        fmt.Println(err)
        return
    }
    fmt.Println("range format:", rf)
}

func rangeFormat(a []int) (string, error) {
    if len(a) == 0 {
        return "", nil
    }
    var parts []string
    for n1 := 0; ; {
        n2 := n1 + 1
        for n2 < len(a) && a[n2] == a[n2-1]+1 {
            n2++
        }
        s := strconv.Itoa(a[n1])
        if n2 == n1+2 {
            s += "," + strconv.Itoa(a[n2-1])
        } else if n2 > n1+2 {
            s += "-" + strconv.Itoa(a[n2-1])
        }
        parts = append(parts, s)
        if n2 == len(a) {
            break
        }
        if a[n2] == a[n2-1] {
            return "", errors.New(fmt.Sprintf(
                "sequence repeats value %d", a[n2]))
        }
        if a[n2] < a[n2-1] {
            return "", errors.New(fmt.Sprintf(
                "sequence not ordered: %d < %d", a[n2], a[n2-1]))
        }
        n1 = n2
    }
    return strings.Join(parts, ","), nil
}

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