diff --git a/src/main/java/com/ximo/datastructuresinaction/algorithmsfourthedition/Chapter01.java b/src/main/java/com/ximo/datastructuresinaction/algorithmsfourthedition/Chapter01.java
new file mode 100644
index 0000000..88f96fc
--- /dev/null
+++ b/src/main/java/com/ximo/datastructuresinaction/algorithmsfourthedition/Chapter01.java
@@ -0,0 +1,41 @@
+package com.ximo.datastructuresinaction.algorithmsfourthedition;
+
+/**
+ * @author xikl
+ * @date 2020/4/25
+ */
+public class Chapter01 {
+
+    public static boolean isPrime(int n) {
+        // 大于1的数字才是
+        if (n < 2) {
+            return false;
+        }
+
+        // 2 和 3 本身只有1和本身
+        if (n == 2 || n == 3) {
+            return true;
+        }
+
+        // 排除偶数
+        if (n % 2 == 0) {
+            return false;
+        }
+
+        // 根据定理
+        // 避免求根号，改为平方
+        for (int i = 2; i * i <= n; i++) {
+            if (n % i == 0) {
+                return false;
+            }
+        }
+
+        return true;
+    }
+
+    public static void main(String[] args) {
+        System.out.println(isPrime(13));
+    }
+
+
+}