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feat: complete Dart codes for chapter_hashing (#566)

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liuyuxin
2023-06-25 20:57:37 +08:00
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parent ff58d4113c
commit 62e8f0df50
7 changed files with 415 additions and 3 deletions
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codes/dart/chapter_hashing/simple_hash.dart
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/**
* File: simple_hash.dart
* Created Time: 2023-06-25
* Author: liuyuxin (gvenusleo@gmail.com)
*/
/* 加法哈希 */
int addHash(String key) {
int hash = 0;
final int MODULUS = 1000000007;
for (int i = 0; i < key.length; i++) {
hash = (hash + key.codeUnitAt(i)) % MODULUS;
}
return hash;
}
/* 乘法哈希 */
int mulHash(String key) {
int hash = 0;
final int MODULUS = 1000000007;
for (int i = 0; i < key.length; i++) {
hash = (31 * hash + key.codeUnitAt(i)) % MODULUS;
}
return hash;
}
/* 异或哈希 */
int xorHash(String key) {
int hash = 0;
final int MODULUS = 1000000007;
for (int i = 0; i < key.length; i++) {
hash ^= key.codeUnitAt(i);
}
return hash & MODULUS;
}
/* 旋转哈希 */
int rotHash(String key) {
int hash = 0;
final int MODULUS = 1000000007;
for (int i = 0; i < key.length; i++) {
hash = ((hash << 4) ^ (hash >> 28) ^ key.codeUnitAt(i)) % MODULUS;
}
return hash;
}
/* Dirver Code */
void main() {
String key = "Hello 算法";
int hash = addHash(key);
print("加法哈希值为 $hash");
hash = mulHash(key);
print("乘法哈希值为 $hash");
hash = xorHash(key);
print("异或哈希值为 $hash");
hash = rotHash(key);
print("旋转哈希值为 $hash");
}