Add Java and C++ code for the section hash algorithm (#560)

codes/java/chapter_hashing/simple_hash.java

@@ -0,0 +1,66 @@
+/**
+ * File: simple_hash.java
+ * Created Time: 2023-06-21
+ * Author: Krahets (krahets@163.com)
+ */
+
+package chapter_hashing;
+
+public class simple_hash {
+    /* 加法哈希 */
+    static int addHash(String key) {
+        long hash = 0;
+        final int MODULUS = 1000000007;
+        for (char c : key.toCharArray()) {
+            hash = (hash + (int) c) % MODULUS;
+        }
+        return (int) hash;
+    }
+
+    /* 乘法哈希 */
+    static int mulHash(String key) {
+        long hash = 0;
+        final int MODULUS = 1000000007;
+        for (char c : key.toCharArray()) {
+            hash = (31 * hash + (int) c) % MODULUS;
+        }
+        return (int) hash;
+    }
+
+    /* 异或哈希 */
+    static int xorHash(String key) {
+        int hash = 0;
+        final int MODULUS = 1000000007;
+        for (char c : key.toCharArray()) {
+            System.out.println((int)c);
+            hash ^= (int) c;
+        }
+        return hash & MODULUS;
+    }
+
+    /* 旋转哈希 */
+    static int rotHash(String key) {
+        long hash = 0;
+        final int MODULUS = 1000000007;
+        for (char c : key.toCharArray()) {
+            hash = ((hash << 4) ^ (hash >> 28) ^ (int) c) % MODULUS;
+        }
+        return (int) hash;
+    }
+
+    public static void main(String[] args) {
+        String key = "Hello 算法";
+
+        int hash = addHash(key);
+        System.out.println("加法哈希值为 " + hash);
+
+        hash = mulHash(key);
+        System.out.println("乘法哈希值为 " + hash);
+
+        hash = xorHash(key);
+        System.out.println("异或哈希值为 " + hash);
+
+        hash = rotHash(key);
+        System.out.println("旋转哈希值为 " + hash);
+    }
+}