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