Add Depth First Search in Go

archive/g/go/depth-first-search.go

@@ -0,0 +1,89 @@
+package main
+
+import (
+	"fmt"
+	"os"
+	"strconv"
+	"strings"
+)
+
+const usage = `Usage: please provide a tree in an adjacency matrix form ("0, 1, 1, 0, 0, 1, 0, 0, 0, 0, 1, 0, 0, 1, 1, 0, 0, 1, 0, 0, 0, 0, 1, 0, 0") together with a list of vertex values ("1, 3, 5, 2, 4") and the integer to find ("4")`
+
+type Graph struct {
+	matrix []int
+	values []int
+	size   int
+}
+
+func main() {
+	if len(os.Args) != 4 {
+		printUsage()
+	}
+
+	matrix, errM := parseList(os.Args[1])
+	values, errV := parseList(os.Args[2])
+	target, errT := strconv.Atoi(os.Args[3])
+
+	if errM != nil || errV != nil || errT != nil {
+		printUsage()
+	}
+
+	n := len(values)
+	if len(matrix) != n*n || n == 0 {
+		printUsage()
+	}
+
+	g := &Graph{
+		matrix: matrix,
+		values: values,
+		size:   n,
+	}
+
+	visited := make([]bool, n)
+	if g.DFS(0, target, visited) {
+		fmt.Println("true")
+	} else {
+		fmt.Println("false")
+	}
+}
+
+func (g *Graph) DFS(curr, target int, visited []bool) bool {
+	if g.values[curr] == target {
+		return true
+	}
+
+	visited[curr] = true
+
+	for neighbor := 0; neighbor < g.size; neighbor++ {
+		edgeExists := g.matrix[curr*g.size+neighbor] == 1
+		if edgeExists && !visited[neighbor] {
+			if g.DFS(neighbor, target, visited) {
+				return true
+			}
+		}
+	}
+
+	return false
+}
+
+func parseList(input string) ([]int, error) {
+	if strings.TrimSpace(input) == "" {
+		return nil, fmt.Errorf("empty input")
+	}
+
+	parts := strings.Split(input, ",")
+	nums := make([]int, 0, len(parts))
+	for _, p := range parts {
+		val, err := strconv.Atoi(strings.TrimSpace(p))
+		if err != nil {
+			return nil, err
+		}
+		nums = append(nums, val)
+	}
+	return nums, nil
+}
+
+func printUsage() {
+	fmt.Println(usage)
+	os.Exit(1)
+}