Create 1048-longest-string-chain.kt

Author: a93a

kotlin/1048-longest-string-chain.kt

@@ -0,0 +1,54 @@
+//dfs
+class Solution {
+    fun longestStrChain(words: Array<String>): Int {
+        val wordList = words.toHashSet()
+        val dp = HashMap<String, Int>()
+
+        fun dfs(word: String, len: Int): Int {
+            if (word !in wordList) return 0
+            if ("$word:$len" in dp) return dp["$word:$len"]!!
+            
+            var res = len
+            for (i in 0 until 26) {
+                for (j in 0..word.length) {
+                    val nextWord = word.substring(0, j) + ('a' + i) + word.substring(j, word.length) 
+                    res = maxOf(res, dfs(nextWord, len + 1))
+                }
+            }
+
+            dp["$word:$len"] = res
+            return res        
+        }
+
+        var res = 1
+        for (word in wordList) {
+            res = maxOf(res, dfs(word, 1))
+        }
+
+        return res
+    }
+}
+
+//dp
+class Solution {
+    fun longestStrChain(words: Array<String>): Int {
+        words.sortBy { it.length }
+        val dp = HashMap<String, Int>()
+
+        var res = 0
+        for (word in words) {
+            var cur = 1
+            for (i in 0 until word.length) {
+                val nextWord = word.substring(0, i) + word.substring(i + 1)
+                dp[nextWord]?.let {
+                    cur = maxOf(cur, it + 1)
+                }
+            }
+
+            dp[word] = cur
+            res = maxOf(res, cur)
+        }
+
+        return res
+    }
+}