You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
66 lines
1.6 KiB
66 lines
1.6 KiB
/**
|
|
* 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()) {
|
|
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);
|
|
}
|
|
}
|