leetcode-go/basis/algorithms/graph/bellman-ford.go

package main

import (
	"fmt"
	"math"
)

func main() {
	var n, m, src int
	fmt.Scan(&n, &m, &src)
	adj := make([][]int, n)
	length := make([][]int, n)
	for i := range length {
		length[i] = make([]int, n)
	}
	for i := 0; i < m; i++ {
		var u, v, l int
		fmt.Scan(&u, &v, &l)
		adj[u] = append(adj[u], v)
		length[u][v] = l
	}
	dist, prev := bellmanFord(adj, length, src)
	fmt.Println(dist)
	fmt.Println(prev)
}

func bellmanFord(adj [][]int, length [][]int, src int) ([]int, []int) {
	n := len(adj)
	dist := make([]int, n)
	prev := make([]int, n)
	for i := 0; i < n; i++ {
		dist[i] = math.MaxInt32
		prev[i] = -1
	}
	dist[src] = 0
	for updated := true; updated; updated = false {
		for u := range adj {
			for _, v := range adj[u] {
				if alt := dist[u] + length[u][v]; alt < dist[v] {
					dist[v] = alt
					prev[v] = u
					updated = true
				}
			}
		}
	}
	return dist, prev
}