golang 有向无环图代码

以下是一个使用Golang实现有向无环图的代码示例：

package main

import (
    "fmt"
)

type Graph struct {
    nodes []int
    edges map[int][]int
}

func (g *Graph) addNode(node int) {
    g.nodes = append(g.nodes, node)
}

func (g *Graph) addEdge(from, to int) {
    if g.edges == nil {
        g.edges = make(map[int][]int)
    }
    g.edges[from] = append(g.edges[from], to)
}

func (g *Graph) topologicalSort() []int {
    inDegree := make(map[int]int)
    for _, node := range g.nodes {
        inDegree[node] = 0
    }
    for _, edges := range g.edges {
        for _, to := range edges {
            inDegree[to]++
        }
    }
    queue := []int{}
    for node, degree := range inDegree {
        if degree == 0 {
            queue = append(queue, node)
        }
    }
    result := []int{}
    for len(queue) > 0 {
        node := queue[0]
        queue = queue[1:]
        result = append(result, node)
        for _, to := range g.edges[node] {
            inDegree[to]--
            if inDegree[to] == 0 {
                queue = append(queue, to)
            }
        }
    }
    return result
}

func main() {
    g := Graph{}
    g.addNode(1)
    g.addNode(2)
    g.addNode(3)
    g.addNode(4)
    g.addEdge(1, 2)
    g.addEdge(1, 3)
    g.addEdge(2, 4)
    g.addEdge(3, 4)
    sorted := g.topologicalSort()
    fmt.Println(sorted)
}