034

Author: TipsyPixie

README.md

@@ -50,4 +50,5 @@ Number | Difficulty | Asked By
 [#31](problem031) | EASY | Google
 [#32](problem032) | HARD | Jane Street
 [#33](problem033) | EASY | Microsoft
+[#34](problem034) | MEDIUM | Quora
 

problem034/README.md

@@ -0,0 +1,11 @@
+## Daily Coding Problem: Problem #34 [MEDIUM]
+
+Good morning! Here's your coding interview problem for today.
+
+This problem was asked by Quora.
+
+Given a string, find the palindrome that can be made by inserting the fewest number of characters as possible anywhere in the word. If there is more than one palindrome of minimum length that can be made, return the lexicographically earliest one (the first one alphabetically).
+
+For example, given the string "race", you should return "ecarace", since we can add three letters to it (which is the smallest amount to make a palindrome). There are seven other palindromes that can be made from "race" by adding three letters, but "ecarace" comes first alphabetically.
+
+As another example, given the string "google", you should return "elgoogle".

problem034/problem034.go

@@ -0,0 +1,33 @@
+package problem034
+
+import (
+	"fmt"
+)
+
+func minString(s1 string, s2 string) string {
+	if s1 <= s2 {
+		return s1
+	}
+	return s2
+}
+
+func ClosestPalindrome(word string) string {
+	if len(word) <= 1 {
+		return word
+	}
+
+	firstCharacter, lastCharacter := word[0], word[len(word)-1]
+	if firstCharacter == lastCharacter {
+		return fmt.Sprintf("%c%s%c", firstCharacter, ClosestPalindrome(word[1:len(word)-1]), lastCharacter)
+	}
+
+	candidate1 := fmt.Sprintf("%c%s%c", firstCharacter, ClosestPalindrome(word[1:]), firstCharacter)
+	candidate2 := fmt.Sprintf("%c%s%c", lastCharacter, ClosestPalindrome(word[:len(word)-1]), lastCharacter)
+	if len(candidate1) < len(candidate2) {
+		return candidate1
+	} else if len(candidate1) == len(candidate2) {
+		return minString(candidate1, candidate2)
+	} else {
+		return candidate2
+	}
+}

problem034/problem034_test.go

@@ -0,0 +1,15 @@
+package problem034
+
+import "testing"
+
+func TestClosestPalindrome(t *testing.T) {
+	result := ClosestPalindrome("race")
+	if result != "ecarace" {
+		t.Fail()
+	}
+
+	result = ClosestPalindrome("google")
+	if result != "elgoogle" {
+		t.Fail()
+	}
+}