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src/main/kotlin/p32xx/Problem3291.kt

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+package p32xx
+
+import util.expect
+
+fun main() {
+    class Solution {
+        fun minValidStrings(words: Array<String>, target: String): Int {
+            class Trie(val depth: Int) {
+                val children = arrayOfNulls<Trie>(26)
+            }
+
+            val root = Trie(0)
+            words.forEach {
+                var current = root
+                it.forEach { ch ->
+                    current = current.children[ch - 'a'] ?: Trie(current.depth + 1).also {
+                        current.children[ch - 'a'] = it
+                    }
+                }
+            }
+
+            var dp = hashMapOf(root to 1)
+
+            target.forEach { ch ->
+                val newDp = hashMapOf<Trie, Int>()
+                var min = Int.MAX_VALUE
+                dp.forEach { (node, count) ->
+                    node.children[ch - 'a']?.also {
+                        newDp[it] = count
+                        min = minOf(min, count)
+                    }
+                }
+
+                if (min < Int.MAX_VALUE) {
+                    newDp[root] = min + 1
+                }
+
+                dp = newDp
+            }
+
+            return dp.values.minOrNull() ?: -1
+        }
+    }
+
+    expect {
+        Solution().minValidStrings(
+            arrayOf(
+                "abc", "aaaaa", "bcdef"
+            ), "aabcdabc"
+        )
+    }
+}