Run Length

ardallie · ardallie · commit 5dbf768519b2 · 2021-08-17T02:27:03.000+01:00
diff --git a/src/medium/RunLength.java b/src/medium/RunLength.java
@@ -0,0 +1,50 @@
+package medium;
+
+/**
+ * Have the function RunLength(str) take the str parameter being passed
+ * and return a compressed version of the string using the Run-length encoding algorithm.
+ * ---
+ * This algorithm works by taking the occurrence of each repeating character
+ * and outputting that number along with a single character of the repeating sequence.
+ * ---
+ * For example: "wwwggopp" would return 3w2g1o2p.
+ * The string will not contain any numbers, punctuation, or symbols.
+ */
+public class RunLength {
+
+  /**
+   * Run Length function.
+   *
+   * @param str input string
+   * @return a compressed version of the string
+   */
+  private static String runLength(String str) {
+    StringBuilder output = new StringBuilder();
+    int count = 0;
+    char prev = str.charAt(0);
+    for (int i = 0; i < str.length(); i++) {
+      if (str.charAt(i) == prev) {
+        count++;
+      } else {
+        output.append(count).append(prev);
+        count = 1;
+        prev = str.charAt(i);
+      }
+    }
+    output.append(count).append(prev);
+    return output.toString();
+  }
+
+  /**
+   * Entry point.
+   *
+   * @param args command line arguments
+   */
+  public static void main(String[] args) {
+    var result1 = runLength("ultrarevolutionaries");
+    System.out.println(result1);
+    var result2 = runLength("underworld");
+    System.out.println(result2);
+  }
+
+}
