Count and say done

Author: rampatra

src/main/java/com/leetcode/strings/CountAndSay.java

@@ -0,0 +1,47 @@
+package com.leetcode.strings;
+
+/**
+ * Problem: https://leetcode.com/problems/count-and-say/
+ *
+ * @author rampatra
+ * @since 2019-04-20
+ */
+public class CountAndSay {
+
+    /**
+     * Time complexity:
+     * Runtime: <a href="https://leetcode.com/submissions/detail/223728660/">1 ms</a>.
+     *
+     * @param n
+     * @return
+     */
+    public static String countAndSay(int n) {
+        if (n == 1) return "1";
+
+        String s = countAndSay(n - 1);
+        StringBuilder sb = new StringBuilder();
+        int count = 0;
+
+        for (int i = 0; i < s.length(); i++) {
+            count++;
+
+            if (i + 1 >= s.length() || s.charAt(i) != s.charAt(i + 1)) {
+                sb.append(count);
+                sb.append(s.charAt(i));
+                count = 0;
+            }
+        }
+
+        return sb.toString();
+    }
+
+    public static void main(String[] args) {
+        System.out.println(countAndSay(1));
+        System.out.println(countAndSay(2));
+        System.out.println(countAndSay(3));
+        System.out.println(countAndSay(4));
+        System.out.println(countAndSay(5));
+        System.out.println(countAndSay(6));
+        System.out.println(countAndSay(10));
+    }
+}