Merge pull request #10 from fabiothiroki/strstr

[WIP] Implementing strstr

Author: fabiothiroki

string/strstr/README.md

@@ -0,0 +1,3 @@
+# Implement strStr()
+
+Return the index of the first occurrence of needle in haystack, or -1 if needle is not part of haystack.

string/strstr/strstr.go

@@ -0,0 +1,51 @@
+package strstr
+
+// StrStr implements the respective method of C++
+func StrStr(haystack string, needle string) int {
+
+	if len(needle) == 0 {
+		return 0
+	}
+
+	if len(needle) > len(haystack) {
+		return -1
+	}
+
+	foundIndex := -1
+	j := -1
+
+	for i := range haystack {
+
+		if foundIndex == -1 {
+			if haystack[i] == needle[0] {
+				if len(needle) == 1 {
+					return i
+				}
+
+				foundIndex = i
+				j = 1
+				continue
+			} else if len(haystack)-i <= len(needle) {
+				return -1
+			} else {
+				continue
+			}
+		}
+
+		if foundIndex != -1 {
+			if haystack[i] == needle[j] {
+
+				if j == len(needle)-1 {
+					return foundIndex
+				}
+				j++
+
+			} else {
+				foundIndex = -1
+			}
+		}
+
+	}
+
+	return foundIndex
+}

string/strstr/strstr_test.go

@@ -0,0 +1,48 @@
+package strstr
+
+import "testing"
+
+func TestHello(t *testing.T) {
+
+	r := StrStr("hello", "ll")
+
+	if r != 2 {
+		t.Errorf("Got: %d, want: %d.", r, 2)
+	}
+}
+
+func TestNotFound(t *testing.T) {
+
+	r := StrStr("aaaaa", "bba")
+
+	if r != -1 {
+		t.Errorf("Got: %d, want: %d.", r, -1)
+	}
+}
+
+func TestReset(t *testing.T) {
+
+	r := StrStr("aaabaaaabb", "abb")
+
+	if r != 7 {
+		t.Errorf("Got: %d, want: %d.", r, 7)
+	}
+}
+
+func TestShortNeedle(t *testing.T) {
+
+	r := StrStr("aaa", "a")
+
+	if r != 0 {
+		t.Errorf("Got: %d, want: %d.", r, 0)
+	}
+}
+
+func TestBigNeedle(t *testing.T) {
+
+	r := StrStr("aaa", "aaaa")
+
+	if r != -1 {
+		t.Errorf("Got: %d, want: %d.", r, -1)
+	}
+}