福大大 答案2021-04-21：
Dijkstra算法是一种基于贪心策略的算法。每次新扩展一个路程最短的点，更新与其相邻的点的路程。时间紧，未完成。
代码用golang编写。代码如下：
package main
import (
"fmt"
"math"
)
func main() {
fmt.Println("")
}
func dijkstra1(from *Node) map[*Node]int {
distanceMap := make(map[*Node]int)
distanceMap[from] = 0
// 打过对号的点
selectedNodes := make(map[*Node]struct{})
minNode := getMinDistanceAndUnselectedNode(distanceMap, selectedNodes)
for minNode != nil {
// 原始点 -> minNode(跳转点) 最小距离distance
distance := distanceMap[minNode]
for _,edge := range minNode.edges {
toNode := edge.to
if _,ok:=distanceMap[toNode];!ok {
distanceMap[toNode]= distance+edge.weight
} else { // toNode
distanceMap[edge.to]=getMin(distanceMap[toNode], distance+edge.weight))
}
}
selectedNodes[minNode]= struct{}{}
minNode = getMinDistanceAndUnselectedNode(distanceMap, selectedNodes)
}
return distanceMap
}
func getMin(a int,b int)int{
if a<b{
return a
}else{
return b
}
}
func getMinDistanceAndUnselectedNode(distanceMap map[*Node]int, touchedNodes map[*Node]struct{}) *Node {
var minNode *Node
minDistance := math.MaxInt32
for k, v := range distanceMap {
node := k
distance := v
_, ok := touchedNodes[node]
if !ok && distance < minDistance {
minNode = node
minDistance = distance
}
}
return minNode
}
type Edge struct {
weight int
from *Node
to *Node
}
// 点结构的描述
type Node struct {
value int
in int
out int
nexts []*Node
edges []*Edge
}
type Graph struct {
nodes map[int]*Node
edges map[*Edge]struct{}
}
左神java代码
