diff --git a/0028_Find_the_Index_of_the_First_Occurrence_in_a_String/0028_Find_the_Index_of_the_First_Occurrence_in_a_String.go b/0028_Find_the_Index_of_the_First_Occurrence_in_a_String/0028_Find_the_Index_of_the_First_Occurrence_in_a_String.go
new file mode 100644
index 0000000..32a7e03
--- /dev/null
+++ b/0028_Find_the_Index_of_the_First_Occurrence_in_a_String/0028_Find_the_Index_of_the_First_Occurrence_in_a_String.go
@@ -0,0 +1,36 @@
+package leetcode_0028_Find_the_Index_of_the_First_Occurrence_in_a_String
+
+func strStr(haystack string, needle string) int {
+	if len(needle) >= len(haystack) && needle != haystack {
+		return -1
+	}
+
+	haystack_len := len(haystack)
+	needle_len := len(needle)
+	res := -1
+	i := 0
+	j := 0
+	for i < haystack_len {
+		if haystack[i] == needle[j] {
+			if res == -1 {
+				res = i
+			}
+			i++
+			j++
+			if j == needle_len {
+				return res
+			}
+		} else if res >= 0 {
+			i = res + 1
+			j = 0
+			res = -1
+		} else {
+			i++
+			j = 0
+		}
+	}
+	if j < needle_len {
+		return -1
+	}
+	return res
+}
diff --git a/0028_Find_the_Index_of_the_First_Occurrence_in_a_String/0028_Find_the_Index_of_the_First_Occurrence_in_a_String_test.go b/0028_Find_the_Index_of_the_First_Occurrence_in_a_String/0028_Find_the_Index_of_the_First_Occurrence_in_a_String_test.go
new file mode 100644
index 0000000..ecd5237
--- /dev/null
+++ b/0028_Find_the_Index_of_the_First_Occurrence_in_a_String/0028_Find_the_Index_of_the_First_Occurrence_in_a_String_test.go
@@ -0,0 +1,63 @@
+package leetcode_0028_Find_the_Index_of_the_First_Occurrence_in_a_String
+
+import "testing"
+
+func Test_strStr(t *testing.T) {
+	type args struct {
+		haystack string
+		needle   string
+	}
+	tests := []struct {
+		name string
+		args args
+		want int
+	}{
+		{
+			name: "Test 1",
+			args: args{
+				haystack: "xsadbutsad",
+				needle:   "sad",
+			},
+			want: 1,
+		},
+		{
+			name: "Test 2",
+			args: args{
+				haystack: "leetcode",
+				needle:   "leeto",
+			},
+			want: -1,
+		},
+		{
+			name: "Test 3",
+			args: args{
+				haystack: "sadbutsad",
+				needle:   "sad",
+			},
+			want: 0,
+		},
+		{
+			name: "Test 4",
+			args: args{
+				haystack: "mississippi",
+				needle:   "issip",
+			},
+			want: 4,
+		},
+		{
+			name: "Test 5",
+			args: args{
+				haystack: "mississi",
+				needle:   "issip",
+			},
+			want: -1,
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			if got := strStr(tt.args.haystack, tt.args.needle); got != tt.want {
+				t.Errorf("strStr() = %v, want %v", got, tt.want)
+			}
+		})
+	}
+}
diff --git a/0066_Plus_One/0066_Plus_One.go b/0066_Plus_One/0066_Plus_One.go
new file mode 100644
index 0000000..086fba4
--- /dev/null
+++ b/0066_Plus_One/0066_Plus_One.go
@@ -0,0 +1,19 @@
+package leetcode_0066_Plus_One
+
+func plusOne(digits []int) []int {
+	inc := 1
+	for i := len(digits) - 1; i >= 0; i-- {
+		digits[i] = digits[i] + inc
+		if digits[i] == 10 {
+			inc = 1
+			digits[i] = 0
+		} else {
+			inc = 0
+		}
+	}
+	if inc > 0 {
+		digits = append([]int{inc}, digits...)
+	}
+
+	return digits
+}
diff --git a/0066_Plus_One/0066_Plus_One_test.go b/0066_Plus_One/0066_Plus_One_test.go
new file mode 100644
index 0000000..9849c85
--- /dev/null
+++ b/0066_Plus_One/0066_Plus_One_test.go
@@ -0,0 +1,46 @@
+package leetcode_0066_Plus_One
+
+import (
+	"reflect"
+	"testing"
+)
+
+func Test_plusOne(t *testing.T) {
+	type args struct {
+		digits []int
+	}
+	tests := []struct {
+		name string
+		args args
+		want []int
+	}{
+		{
+			name: "Test 1",
+			args: args{
+				digits: []int{1, 2, 3},
+			},
+			want: []int{1, 2, 4},
+		},
+		{
+			name: "Test 2",
+			args: args{
+				digits: []int{4, 3, 2, 1},
+			},
+			want: []int{4, 3, 2, 2},
+		},
+		{
+			name: "Test 3",
+			args: args{
+				digits: []int{9, 9, 9},
+			},
+			want: []int{1, 0, 0, 0},
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			if got := plusOne(tt.args.digits); !reflect.DeepEqual(got, tt.want) {
+				t.Errorf("plusOne() = %v, want %v", got, tt.want)
+			}
+		})
+	}
+}