diff --git a/basic/src/main/java/lo/basic/Issue12.java b/basic/src/main/java/lo/basic/Issue12.java
new file mode 100644
index 0000000..862ab66
--- /dev/null
+++ b/basic/src/main/java/lo/basic/Issue12.java
@@ -0,0 +1,116 @@
+package lo.basic;
+
+public class Issue12 {
+
+	public static void main(String[] args) {
+		int input = 5;
+		System.out.println("v1");
+		v1(input);
+		System.out.println("v2");
+		v2(input);
+		System.out.println("v3");
+		v3(input);
+		System.out.println("v4");
+		v4(input);
+		System.out.println("v5");
+		v5(input, new char[] {'5', '4', '8', '7'});
+	}
+
+	public static void v1(int x) {
+		int counter = 1;
+		for (int i = 0; i < x; i++) {
+			for (int i2 = i + 1; i2 < x; i2++) {
+				System.out.print(" ");
+			}
+			for (int i2 = 0; i2 <= i * 2; i2++) {
+				if (counter < 9) {
+					System.out.print(counter);
+					counter += 1;
+				} else {
+					System.out.print(counter);
+					counter = 0;
+				}
+			}
+			System.out.println();
+		}
+	}
+
+	public static void v2(int x) {
+		int counter = 1;
+		for (int i = 0; i < x; i++) {
+			for (int i2 = 0; i2 < x * 2 - 1; i2++) {
+				if (i2 < x - i - 1 || i2 > x + i - 1) {
+					System.out.print(" ");
+				} else {
+					if (counter < 9) {
+						System.out.print(counter);
+						counter += 1;
+					} else {
+						System.out.print(counter);
+						counter = 0;
+					}
+				}
+			}
+			System.out.println();
+		}
+	}
+
+	public static void v3(int x) {
+		int[] list = new int[] { 0, 1, 2, 3, 4, 5, 6, 7, 8, 9 };
+		int index = 1;
+		int limit = x * 2;
+		for (int i = 1; i < limit; i += 2) {
+			for (int i2 = 1; i2 < limit - i; i2 += 2) {
+				System.out.print(" ");
+			}
+			for (int i2 = 0; i2 < i; i2++) {
+				if (index > 9) {
+					index = 0;
+				}
+				System.out.print(list[index]);
+				index += 1;
+			}
+			System.out.println();
+		}
+	}
+
+	/**
+	 * L89 直接寫 10 這個數字不恰當，像是之前提過的 magic 9，
+	 * 應該寫 list.length，這樣與變數 list 的長度才有關連性。
+	 */
+	public static void v4(int x) {
+		int[] list = new int[] { 0, 1, 2, 3, 4, 5, 6, 7, 8, 9 };
+		int index = 1;
+		int limit = x * 2;
+		for (int i = 1; i < limit; i += 2) {
+			for (int i2 = 1; i2 < limit - i; i2 += 2) {
+				System.out.print(" ");
+			}
+			for (int i2 = 0; i2 < i; i2++) {
+				System.out.print(list[index]);
+				index = (index + 1) % 10;
+			}
+			System.out.println();
+		}
+	}
+
+	/**
+	 * v5 傳入的 array 可以為空的 array，
+	 * 例如 v5(input, new char[] {})，
+	 * 程式會執行但是會發生被除數為 0 的錯誤。
+	 */
+	public static void v5(int x, char[] array) {
+		int index = 0;
+		int limit = x * 2;
+		for (int i = 1; i < limit; i += 2) {
+			for (int i2 = 1; i2 < limit - i; i2 += 2) {
+				System.out.print(" ");
+			}
+			for (int i2 = 0; i2 < i; i2++) {
+				System.out.print(array[index % array.length]);
+				index = index + 1;
+			}
+			System.out.println();
+		}
+	}
+}
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