added DFS AND BSF to graphs

graphs/algorithms.go

@@ -0,0 +1,81 @@
+package graphs
+
+import (
+	"datastructures/linear"
+)
+
+// DFS() -> Depth First traversal, returns ordered slice or nil if start point
+// is invalid
+func (graph *Graph[T]) DFS(start T) []T {
+	// sanity check
+	if _, ok := graph.adjList[start]; !ok {
+		return nil
+	}
+
+	visited := make(map[T]bool, len(graph.adjList))
+	ordered := make([]T, 0, graph.Order())
+
+	stack := linear.Stack[T]{}
+
+	stack.Push(start)
+	visited[start] = true
+
+	for stack.Size() > 0 {
+
+		current, err := stack.Pop()
+		if err != nil {
+			break
+		}
+
+		ordered = append(ordered, current)
+
+		for _, neighbor := range graph.adjList[current] {
+			if !visited[neighbor] {
+				visited[neighbor] = true
+				stack.Push(neighbor)
+
+			}
+		}
+
+	}
+
+	return ordered
+}
+
+// BFS() -> Breadth First traversal start, returning the
+// vertices in visit order. Returns nil if start is not in the graph.
+func (graph *Graph[T]) BFS(start T) []T {
+	// sanity check
+	if _, ok := graph.adjList[start]; !ok {
+		return nil
+	}
+
+	visited := make(map[T]bool, len(graph.adjList))
+	ordered := make([]T, 0, graph.Order())
+
+	queue := linear.Queue[T]{}
+
+	queue.Push(start)
+	visited[start] = true
+
+	for queue.Size() > 0 {
+
+		current, err := queue.Pop()
+		if err != nil {
+			break
+		}
+
+		ordered = append(ordered, current)
+
+		for _, neighbor := range graph.adjList[current] {
+			if !visited[neighbor] {
+				visited[neighbor] = true
+				queue.Push(neighbor)
+
+			}
+		}
+
+	}
+
+	return ordered
+}