392. Is Subsequence

Author: amitbansal7

is-subsequence.scala

@@ -0,0 +1,21 @@
+//Runtime: 396 ms
+object Solution {
+    def isSubsequence(s: String, t: String): Boolean = {
+
+        def look(c:Char, t:String, idx:Int):Int = {
+            if(idx >= t.size) -1
+            else if(c == t(idx)) idx
+            else look(c, t, idx+1)
+        }
+
+        def solve(s:String , t:String, i:Int, idx:Int):Boolean = {
+            if(i >= s.size) true
+            else{
+                val idx2 = look(s(i), t, idx+1)
+                if(idx2 == -1) false
+                else solve(s, t, i+1, idx2)
+            }
+        }
+        solve(s, t, 0, -1)
+    }
+}