Add edge case to handle negative rod length in RodCutting algorithm (#5904)

src/main/java/com/thealgorithms/dynamicprogramming/RodCutting.java

@@ -22,6 +22,10 @@ public final class RodCutting {
         if (price == null || price.length == 0) {
             throw new IllegalArgumentException("Price array cannot be null or empty.");
         }
+        if (n < 0) {
+            throw new IllegalArgumentException("Rod length cannot be negative.");
+        }
+
         // Create an array to store the maximum obtainable values for each rod length.
         int[] val = new int[n + 1];
         val[0] = 0;