1

src/main/kotlin/p25xx/Problem2500.kt

@@ -7,9 +7,9 @@ fun main() {
         fun deleteGreatestValue(grid: Array<IntArray>): Int {
             grid.forEach { it.sort() }
 
-            return grid[0].indices.map { i ->
-                grid.map { it[i] }.max()
-            }.sum()
+            return grid[0].indices.sumOf { i ->
+                grid.maxOf { it[i] }
+            }
         }
     }
 

src/main/kotlin/p30xx/Problem3083.kt

@@ -0,0 +1,37 @@
+package p30xx
+
+import util.expect
+
+fun main() {
+    class Solution {
+        fun isSubstringPresent(s: String): Boolean {
+            val befores = Array(26) { hashSetOf<Int>() }
+            val afters = Array(26) { hashSetOf<Int>() }
+
+            s.forEachIndexed { index, ch ->
+                s.getOrNull(index - 1)?.also {
+                    if (it - 'a' in afters[ch - 'a']) {
+                        return true
+                    }
+
+                    befores[ch - 'a'] += it - 'a'
+                }
+                s.getOrNull(index + 1)?.also {
+                    if (it - 'a' in befores[ch - 'a']) {
+                        return true
+                    }
+
+                    afters[ch - 'a'] += it - 'a'
+                }
+            }
+
+            return false
+        }
+    }
+
+    expect {
+        Solution().isSubstringPresent(
+            ""
+        )
+    }
+}