Create 0880-decoded-string-at-index.java

Author: sujal-goswami

java/0880-decoded-string-at-index.java

@@ -0,0 +1,34 @@
+/*
+-----------------------
+  Time Complexity : O(n)
+  Space Complexity = O(1)
+-----------------------
+*/
+
+class Solution {
+    public String decodeAtIndex(String s, int k) {
+        long wordLength = 0;
+        for (char c : s.toCharArray()) {
+            if (Character.isLetter(c)) {
+                wordLength += 1;
+            } else {
+                wordLength *= Character.getNumericValue(c);
+            }
+        }
+
+        for (int i = s.length() - 1; i >= 0; i--) {
+            char c = s.charAt(i);
+            k %= wordLength;
+            if (Character.isLetter(c)) {
+                if (k == 0) {
+                    return String.valueOf(c);
+                } else {
+                    wordLength -= 1;
+                }
+            } else {
+                wordLength /= Character.getNumericValue(c);
+            }
+        }
+        return ""; 
+    }
+}