Q1.4: Palindrome permutation, simplified implementation

ch01/palindrome_permutation.go

@@ -25,3 +25,26 @@ func IsPalindromePermutation(s string) bool {
 
 	return true
 }
+
+// IsPalindromePermutationSimplified returns true if a srting is a palindrome permutation
+// It uses a single for loop to check the permutations
+func IsPalindromePermutationSimplified(s string) bool {
+	set := make(map[rune]int)
+	odd := 0
+
+	for _, c := range s {
+		if c == ' ' {
+			continue
+		}
+
+		set[c]++
+
+		if set[c]%2 != 0 {
+			odd++
+		} else {
+			odd--
+		}
+	}
+
+	return !(odd > 1)
+}

ch01/palindrome_permutation_test.go

@@ -7,4 +7,21 @@ func TestIsPalindromePermutation(t *testing.T) {
 	if !IsPalindromePermutation(s) {
 		t.Errorf("\"%s\" expected to be marked as a palindrome permutation", s)
 	}
+
+	s = "tacos cat"
+	if IsPalindromePermutation(s) {
+		t.Errorf("\"%s\" expected not to be marked as a palindrome permutation", s)
+	}
+}
+
+func TestIsPalindromePermutationSimplified(t *testing.T) {
+	s := "taco cat"
+	if !IsPalindromePermutationSimplified(s) {
+		t.Errorf("\"%s\" expected to be marked as a palindrome permutation", s)
+	}
+
+	s = "tacos cat"
+	if IsPalindromePermutationSimplified(s) {
+		t.Errorf("\"%s\" expected not to be marked as a palindrome permutation", s)
+	}
 }