Improved tasks 620, 1309, 1392

README.md

@@ -498,7 +498,7 @@ implementation 'com.github.javadev:leetcode-in-kotlin:1.36'
 | <!-- --> | <!-- --> | <!-- --> | <!-- --> | <!-- --> | <!-- -->
 |-|-|-|-|-|-
 | 0709 |[To Lower Case](src/main/kotlin/g0701_0800/s0709_to_lower_case/Solution.kt)| Easy | String | 142 | 98.68
-| 1309 |[Decrypt String from Alphabet to Integer Mapping](src/main/kotlin/g1301_1400/s1309_decrypt_string_from_alphabet_to_integer_mapping/Solution.kt)| Easy | String | 129 | 95.45
+| 1309 |[Decrypt String from Alphabet to Integer Mapping](src/main/kotlin/g1301_1400/s1309_decrypt_string_from_alphabet_to_integer_mapping/Solution.kt)| Easy | String | 0 | 100.00
 | 0953 |[Verifying an Alien Dictionary](src/main/kotlin/g0901_1000/s0953_verifying_an_alien_dictionary/Solution.kt)| Easy | Array, String, Hash_Table | 137 | 100.00
 
 #### Day 10 Linked List and Tree

src/main/kotlin/g0601_0700/s0620_not_boring_movies/script.sql

@@ -1,7 +1,6 @@
 # Write your MySQL query statement below
-# #Easy #Database #2023_02_06_Time_305_ms_(59.80%)_Space_0B_(100.00%)
-select id, movie, description, rating from Cinema
-WHERE mod(id,2) = 1
-and
-description not LIKE '%boring%'
-order by rating DESC;
+# #Easy #Database #2025_04_23_Time_259_ms_(64.69%)_Space_0.0_MB_(100.00%)
+SELECT id, movie, description, rating
+FROM Cinema
+WHERE description != 'boring' AND id % 2 != 0
+ORDER BY rating DESC;

src/main/kotlin/g1301_1400/s1309_decrypt_string_from_alphabet_to_integer_mapping/Solution.kt

@@ -1,51 +1,26 @@
 package g1301_1400.s1309_decrypt_string_from_alphabet_to_integer_mapping
 
 // #Easy #String #Programming_Skills_I_Day_9_String
-// #2023_06_05_Time_129_ms_(95.45%)_Space_34.8_MB_(63.64%)
+// #2025_04_24_Time_0_ms_(100.00%)_Space_40.80_MB_(77.78%)
 
 class Solution {
     fun freqAlphabets(s: String): String {
-        val map: MutableMap<String, String> = HashMap()
-        map["1"] = "a"
-        map["2"] = "b"
-        map["3"] = "c"
-        map["4"] = "d"
-        map["5"] = "e"
-        map["6"] = "f"
-        map["7"] = "g"
-        map["8"] = "h"
-        map["9"] = "i"
-        map["10#"] = "j"
-        map["11#"] = "k"
-        map["12#"] = "l"
-        map["13#"] = "m"
-        map["14#"] = "n"
-        map["15#"] = "o"
-        map["16#"] = "p"
-        map["17#"] = "q"
-        map["18#"] = "r"
-        map["19#"] = "s"
-        map["20#"] = "t"
-        map["21#"] = "u"
-        map["22#"] = "v"
-        map["23#"] = "w"
-        map["24#"] = "x"
-        map["25#"] = "y"
-        map["26#"] = "z"
-        val sb = StringBuilder()
-        var i = 0
-        while (i < s.length) {
-            if ((("" + s[i]).toInt() == 1 || ("" + s[i]).toInt() == 2) &&
-                i + 1 < s.length && i + 2 < s.length &&
-                s[i + 2] == '#'
-            ) {
-                sb.append(map[s.substring(i, i + 3)])
-                i += 3
+        val builder = StringBuilder()
+        var i = s.length - 1
+        while (i >= 0) {
+            if (s[i] == '#') {
+                decryptor(builder, i - 1, i - 2, s)
+                i -= 3
             } else {
-                sb.append(map["" + s[i]])
-                i++
+                val ch = (s[i].code - '0'.code + 96).toChar()
+                builder.append(ch)
+                i--
             }
         }
-        return sb.toString()
+        return builder.reverse().toString()
+    }
+
+    private fun decryptor(builder: StringBuilder, a: Int, b: Int, s: String) {
+        builder.append((((s[b].code - '0'.code) * 10 + s[a].code - '0'.code) + 96).toChar())
     }
 }

src/main/kotlin/g1301_1400/s1392_longest_happy_prefix/Solution.kt

@@ -1,25 +1,29 @@
 package g1301_1400.s1392_longest_happy_prefix
 
 // #Hard #String #Hash_Function #String_Matching #Rolling_Hash
-// #2023_06_06_Time_291_ms_(50.00%)_Space_38.1_MB_(100.00%)
+// #2025_04_24_Time_7_ms_(100.00%)_Space_47.37_MB_(25.00%)
 
 class Solution {
     fun longestPrefix(s: String): String {
-        val times = 2
-        var prefixHash: Long = 0
-        var suffixHash: Long = 0
-        var multiplier: Long = 1
-        var len: Long = 0
-        // use some large prime as a modulo to avoid overflow errors, e.g. 10 ^ 9 + 7.
-        val mod: Long = 1000000007
-        for (i in 0 until s.length - 1) {
-            prefixHash = (prefixHash * times + s[i].code.toLong()) % mod
-            suffixHash = (multiplier * s[s.length - i - 1].code.toLong() + suffixHash) % mod
-            if (prefixHash == suffixHash) {
-                len = i.toLong() + 1
+        val c = s.toCharArray()
+        val n = c.size
+        val a = IntArray(n)
+        var max = 0
+        var i = 1
+        while (i < n) {
+            if (c[max] == c[i]) {
+                max++
+                a[i] = max
+                i++
+            } else {
+                if (max > 0) {
+                    max = a[max - 1]
+                } else {
+                    a[i] = 0
+                    i++
+                }
             }
-            multiplier = multiplier * times % mod
         }
-        return s.substring(0, len.toInt())
+        return s.substring(0, a[n - 1])
     }
 }

src/test/kotlin/g1301_1400/s1392_longest_happy_prefix/SolutionTest.kt

@@ -14,4 +14,9 @@ internal class SolutionTest {
     fun longestPrefix2() {
         assertThat(Solution().longestPrefix("ababab"), equalTo("abab"))
     }
+
+    @Test
+    fun longestPrefix3() {
+        assertThat(Solution().longestPrefix("babbb"), equalTo("b"))
+    }
 }