Dijkstra in Go

Dijkstra

in Go

Welcome to the Dijkstra in Go page! Here, you'll find the source code for this program as well as a description of how the program works.

Current Solution

package main

import (
	"fmt"
	"math"
	"os"
	"strconv"
	"strings"
)

const usage = `Usage: please provide three inputs: a serialized matrix, a source node and a destination node`

func main() {
	if len(os.Args) != 4 {
		printUsage()
	}

	matrix, errM := parseList(os.Args[1])
	source, errS := strconv.Atoi(os.Args[2])
	dest, errD := strconv.Atoi(os.Args[3])

	if errM != nil || errS != nil || errD != nil {
		printUsage()
	}

	nFloat := math.Sqrt(float64(len(matrix)))
	n := int(nFloat)
	if nFloat != float64(n) || n == 0 {
		printUsage()
	}

	if source < 0 || source >= n || dest < 0 || dest >= n {
		printUsage()
	}

	for _, w := range matrix {
		if w < 0 {
			printUsage()
		}
	}

	cost, reachable := dijkstra(matrix, n, source, dest)
	if !reachable {
		printUsage()
	}

	fmt.Println(cost)
}

func dijkstra(matrix []int, n, start, end int) (int, bool) {
	dist := make([]int, n)
	visited := make([]bool, n)

	for i := range dist {
		dist[i] = math.MaxInt32
	}
	dist[start] = 0

	for i := 0; i < n; i++ {
		u := -1
		minDist := math.MaxInt32

		for v := 0; v < n; v++ {
			if !visited[v] && dist[v] < minDist {
				u = v
				minDist = dist[v]
			}
		}

		if u == -1 {
			break
		}

		visited[u] = true
		if u == end {
			return dist[u], true
		}

		for v := 0; v < n; v++ {
			weight := matrix[u*n+v]
			if weight > 0 && !visited[v] {
				newDist := dist[u] + weight
				if newDist < dist[v] {
					dist[v] = newDist
				}
			}
		}
	}

	if dist[end] == math.MaxInt32 {
		return 0, false
	}
	return dist[end], true
}

func parseList(input string) ([]int, error) {
	if strings.TrimSpace(input) == "" {
		return nil, fmt.Errorf("empty input")
	}

	parts := strings.Split(input, ",")
	nums := make([]int, 0, len(parts))
	for _, p := range parts {
		val, err := strconv.Atoi(strings.TrimSpace(p))
		if err != nil {
			return nil, err
		}
		nums = append(nums, val)
	}
	return nums, nil
}

func printUsage() {
	fmt.Println(usage)
	os.Exit(1)
}

Dijkstra in Go was written by:

• Ștefan-Iulian Alecu

If you see anything you'd like to change or update, please consider contributing.

How to Implement the Solution

No 'How to Implement the Solution' section available. Please consider contributing.

How to Run the Solution

No 'How to Run the Solution' section available. Please consider contributing.