散列中的折叠方法
折叠法在 哈希 : 它把一个键值分解成精确的段，这些段被相加形成一个哈希值，再来看看另一种技术，就是在相加之前对每个段单独应用一个乘法哈希函数。有些折叠方法更进一步，在添加之前，每隔一段就反转一次。这种折叠方式独立于分布。
算法:
- The folding method used to create the hash function starts with dividing the item into equal-sized blocks, that is, the last block may be of different sizes.
- The result of adding these bits together is the hash value, h (x) = (a+b+c) mod m , where a, b and c represent the preprocessed key divided into three parts, m is the table size, and * In other words, the sum of the three parts of the preprocessing key is divided by the table size. The rest is the hash key.T21】
*说明:*
*示例 1:* 任务是将密钥 123456789 折叠成十个空格的哈希表(0 到 9)。
The key is given, and it is said that *x is 123,456,789 and the table size (namely m = 10). Because it can divide x into three parts in any order. Let's divide it equally. Therefore, a = 123, b = 456 and c = 789. 【t0 h(x)=(a+b+ c)对着 m(123456789)=(123+456+789)对着 10 = 1368 对着 10 = 对着 T3 . Therefore, 123456789 is inserted into the table with address 8 .
*示例 2:* 任务是将密钥 452378912 折叠成十个空格的哈希表(0 到 9)。
The key is given, saying that *x is 452378912 and table size (namely m = 10). Because it can divide x into three parts in any order. Let's divide it equally. Therefore, a = 452, b = 378 and c = 912. 【t0 h(x)=(a+b+ c)对着 m(457822)=(452+378+912)对着 10 = 1742 对着 10 = 对着 T3 . Therefore, 452378912 is inserted in the table with address 2 .
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