Create 0093-restore-ip-addresses.kt

Author: a93a

kotlin/0093-restore-ip-addresses.kt

@@ -0,0 +1,22 @@
+class Solution {
+    fun restoreIpAddresses(s: String): List<String> {
+        val res = mutableListOf<String>()
+
+        fun backTrack(i: Int, dots: Int, cur: String) {
+            if (dots == 4 && i == s.length) {
+                res.add(cur.substring(0, cur.lastIndex))
+                return
+            }
+            if (dots > 4) return
+
+            for (j in i until minOf(i + 3, s.length)) {
+                val digits = s.substring(i, j + 1)
+                if (digits.toInt() <= 255 && (i == j || s[i] != '0'))
+                    backTrack(j + 1, dots + 1, cur + digits + ".")
+            }
+        }
+
+        backTrack(0, 0, "")
+        return res
+    }
+}