2

这是 C# 中 Rabin-Karp 字符串匹配算法的实现......

static void Main(string[] args)
{
  string A = "String that contains a pattern.";
  string B = "pattern";
  ulong siga = 0;
  ulong sigb = 0;
  ulong Q = 100007;
  ulong D = 256;
for (int i = 0; i < B.Length; i++)
{
    siga = (siga * D + (ulong)A[i]) % Q;
    sigb = (sigb * D + (ulong)B[i]) % Q;
}
if (siga == sigb)
{
    Console.WriteLine(string.Format(">>{0}<<{1}", A.Substring(0, B.Length), A.Substring(B.Length)));
    return;
}
ulong pow = 1;
for (int k = 1; k <= B.Length - 1; k++)
    pow = (pow * D) % Q;

for (int j = 1; j <= A.Length - B.Length; j++)
{
    siga = (siga + Q - pow * (ulong)A[j - 1] %Q) % Q;
    siga = (siga * D + (ulong)A[j + B.Length - 1]) % Q;
    if (siga == sigb)
    {
        if (A.Substring(j, B.Length) == B)
        {
            Console.WriteLine(string.Format("{0}>>{1}<<{2}", A.Substring(0, j), 
                                                             A.Substring(j, B.Length), 
                                                             A.Substring(j +B.Length)));
            return;
        }
    }
}
Console.WriteLine("Not copied!");

}

但是如果我更改第二个字符串的位置而不是显示结果未复制但它有一个问题 

 string A = "String that contains a pattern.";
 string B = "pattern";

这里显示未复制

 string A = "String that contains a pattern.";
 string B = "Matches contains a pattern ";

我想检查它是否是从第一个字符串复制的，甚至我会在其中添加一些内容或更改位置，但它不应该有所不同，所以如何更改它，它只会比较字符串中每个单词的哈希值而不是执行它…………

4

1 回答 1

0

改变

string B = "Matches contains a pattern ";

至

string B = "contains a pattern ";

它会起作用

于 2011-12-12T16:44:47.430 回答