Merge pull request #28 from dwij2812/depthFirstSearch

Added Depth First Search

Author: 0xAX

README.md

@@ -35,6 +35,7 @@ Algorithms
   * [binary search](https://en.wikipedia.org/wiki/Binary_search_algorithm)
   * [linear search](https://en.wikipedia.org/wiki/Linear_search)
   * [jump search](https://en.wikipedia.org/wiki/Jump_search)
+  * [depth first search](https://en.wikipedia.org/wiki/Depth-first_search)
   * [breadth-first search](https://en.wikipedia.org/wiki/Breadth-first_search)
 
 #### Collections

searching/depthFirstSearch.go

@@ -0,0 +1,72 @@
+package main
+
+import "fmt"
+
+func getIdx(target int, nodes []int) int {
+	for i := 0; i < len(nodes); i++ {
+		if nodes[i] == target {
+			return i
+		}
+	}
+	return -1
+}
+
+func notExist(target int, slice []int) bool {
+	for i := 0; i < len(slice); i++ {
+		if slice[i] == target {
+			return false
+		}
+	}
+	return true
+}
+
+func dfs(start, end int, nodes []int, edges [][]bool) ([]int, bool) {
+	var route []int
+	var stack []int
+	startIdx := getIdx(start, nodes)
+	stack = append(stack, startIdx)
+	for len(stack) > 0 {
+		now := stack[len(stack)-1]
+		route = append(route, nodes[now])
+		if len(stack) > 1 {
+			stack = stack[:len(stack)-1]
+		} else {
+			stack = stack[:len(stack)-1]
+		}
+		for i := 0; i < len(edges[now]); i++ {
+			if edges[now][i] && notExist(i, stack) {
+				stack = append(stack, i)
+			}
+			edges[now][i] = false
+			edges[i][now] = false
+		}
+		if route[len(route)-1] == end {
+			return route, true
+		}
+	}
+	return nil, false
+}
+
+func main() {
+	nodes := []int{
+		1, 2, 3, 4, 5, 6,
+	}
+	/*
+		sample graph
+		①-②
+		|  |
+		③-④-⑤-⑥
+	*/
+	edges := [][]bool{
+		{false, true, true, false, false, false},
+		{true, false, false, true, false, false},
+		{true, false, false, true, false, false},
+		{false, true, true, false, true, false},
+		{false, false, false, true, false, true},
+		{false, false, false, false, true, false},
+	}
+	start := 1
+	end := 6
+	route, _ := dfs(start, end, nodes, edges)
+	fmt.Println(route)
+}