68 lines
1.5 KiB
Go
68 lines
1.5 KiB
Go
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// Copyright (c) 2016 Bitfury Group Limited
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// Distributed under the MIT software license, see the accompanying
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// file LICENSE or http://www.opensource.org/licenses/mit-license.php
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package graph
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import "container/list"
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func ShortestPathLen(g *Graph, v1, v2 Vertex) (int, error) {
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dist, _, err := bfs(g, v1, v2)
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if err != nil {
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return 0, err
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}
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if _, ok := dist[v2]; !ok {
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return 0, PathNotFoundError
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}
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return dist[v2], nil
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}
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func ShortestPath(g *Graph, v1, v2 Vertex) ([]Vertex, error) {
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_, parent, err := bfs(g, v1, v2)
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if err != nil {
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return nil, err
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}
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if _, ok := parent[v2]; !ok {
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return nil, PathNotFoundError
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}
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path, err := Path(v1, v2, parent)
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if err != nil {
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return nil, err
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}
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return path, nil
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}
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func bfs(g *Graph, v1, v2 Vertex) (map[Vertex]int, map[Vertex]Vertex, error) {
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var queue list.List
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queue.PushBack(v1)
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dist := make(map[Vertex]int)
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parent := make(map[Vertex]Vertex)
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dist[v1] = 0
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for queue.Len() != 0 {
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err := ibfs(g, queue.Front().Value.(Vertex), &queue, dist, parent)
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if err != nil {
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return nil, nil, err
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}
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if _, ok := dist[v2]; ok {
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break
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}
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}
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return dist, parent, nil
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}
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func ibfs(g *Graph, v Vertex, queue *list.List, dist map[Vertex]int, parent map[Vertex]Vertex) error {
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queue.Remove(queue.Front())
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targets, err := g.GetNeighbors(v)
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if err != nil {
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return err
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}
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for to := range targets {
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if _, ok := dist[to]; !ok {
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dist[to] = dist[v] + 1
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parent[to] = v
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queue.PushBack(to)
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}
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}
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return nil
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}
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