add graph seach algo: BFS & DFS

Author: LYDongD

go/31_graph/grap_search.go

@@ -0,0 +1,152 @@
+package grap
+
+import (
+	"container/list"
+	"fmt"
+)
+
+//adjacency table, 无向图
+type Graph struct {
+	adj []*list.List
+	v   int
+}
+
+//init graphh according to capacity
+func newGraph(v int) *Graph {
+	graphh := &Graph{}
+	graphh.v = v
+	graphh.adj = make([]*list.List, v)
+	for i := range graphh.adj {
+		graphh.adj[i] = list.New()
+	}
+	return graphh
+}
+
+//insert as add edge，一条边存2次
+func (self *Graph) addEdge(s int, t int) {
+	self.adj[s].PushBack(t)
+	self.adj[t].PushBack(s)
+}
+
+//search path by BFS
+func (self *Graph) BFS(s int, t int) {
+
+	//todo
+	if s == t {
+		return
+	}
+
+	//init prev
+	prev := make([]int, self.v)
+	for index := range prev {
+		prev[index] = -1
+	}
+
+	//search by queue
+	var queue []int
+	visited := make([]bool, self.v)
+	queue = append(queue, s)
+	visited[s] = true
+	isFound := false
+	for len(queue) > 0 && !isFound {
+		top := queue[0]
+		queue = queue[1:]
+		linkedlist := self.adj[top]
+		for e := linkedlist.Front(); e != nil; e = e.Next() {
+			k := e.Value.(int)
+			if !visited[k] {
+				prev[k] = top
+				if k == t {
+					isFound = true
+					break
+				}
+				queue = append(queue, k)
+				visited[k] = true
+			}
+		}
+	}
+
+	if isFound {
+		printPrev(prev, s, t)
+	} else {
+		fmt.Printf("no path found from %d to %d\n", s, t)
+	}
+
+}
+
+//search by DFS
+func (self *Graph) DFS(s int, t int) {
+
+	prev := make([]int, self.v)
+	for i := range prev {
+		prev[i] = -1
+	}
+
+	visited := make([]bool, self.v)
+	visited[s] = true
+
+	isFound := false
+	self.recurse(s, t, prev, visited, isFound)
+
+	printPrev(prev, s, t)
+}
+
+//recursivly find path
+func (self *Graph) recurse(s int, t int, prev []int, visited []bool, isFound bool) {
+
+	if isFound {
+		return
+	}
+
+	visited[s] = true
+
+	if s == t {
+		isFound = true
+		return
+	}
+
+	linkedlist := self.adj[s]
+	for e := linkedlist.Front(); e != nil; e = e.Next() {
+		k := e.Value.(int)
+		if !visited[k] {
+			prev[k] = s
+			self.recurse(k, t, prev, visited, false)
+		}
+	}
+
+}
+
+//print path recursively
+func printPrev(prev []int, s int, t int) {
+
+	if t == s || prev[t] == -1 {
+		fmt.Printf("%d ", t)
+	} else {
+		printPrev(prev, s, prev[t])
+		fmt.Printf("%d ", t)
+	}
+
+}
+
+//func main() {
+//	graph := newGraph(8)
+//	graph.addEdge(0, 1)
+//	graph.addEdge(0, 3)
+//	graph.addEdge(1, 2)
+//	graph.addEdge(1, 4)
+//	graph.addEdge(2, 5)
+//	graph.addEdge(3, 4)
+//	graph.addEdge(4, 5)
+//	graph.addEdge(4, 6)
+//	graph.addEdge(5, 7)
+//	graph.addEdge(6, 7)
+//
+//	graph.BFS(0, 7)
+//	fmt.Println()
+//	graph.BFS(1, 3)
+//	fmt.Println()
+//	graph.DFS(0, 7)
+//	fmt.Println()
+//	graph.DFS(1, 3)
+//	fmt.Println()
+//}