java代码
import java.util.Scanner; public class Horspool { public static void ShiftTable(char[] p, int[] table){ for (int i = 0; i < 26; i++) { table[i] = p.length; } for (int i = 0; i < p.length - 1; i++) { table[p[i] -‘A‘] = p.length - 1 - i; } } public static int HorspoolMatching(char[] text, char[] template,int[] table){ ShiftTable(template, table); int i = template.length - 1; while(i <= text.length){ int k = 0; while(k < template.length && template[template.length - 1 - k] == text[i-k]) k++; if(k == template.length) return i - template.length +1; else i += table[text[i]-‘A‘]; } return -1; }// Horspool算法 public static int Matching(char[] text, char[] template){ for (int i = 0; i < text.length; i++) { int k = 0; for (; k < template.length; k++) { if(text[i+k] != template[k]) break; } if(k == template.length) return i; } return -1; } // 蛮力法 public static String getRandomString(long length) { System.out.println("正在生成文本"); StringBuffer sb = new StringBuffer(); for (int i = 0; i < length; i++) { long result = 0; result = Math.round(Math.random() * 25 + 97); sb.append(String.valueOf((char) result)); } System.out.println("成功生成"); return sb.toString(); } // 随机生成字符串 public static void main(String[] args) { int[] table = new int[26]; Scanner in = new Scanner(System.in); // System.out.println("输入匹配的文本"); // String te = in.nextLine(); // System.out.println("输入匹配的模板"); // String t = in.nextLine(); String te = getRandomString(100000000); String t = getRandomString(10000); te = te.toUpperCase(); t = t.toUpperCase(); char[] text = te.toCharArray(); char[] template = t.toCharArray(); System.out.println("---------Horspool算法-----------"); long start1=System.currentTimeMillis(); int pos1 = HorspoolMatching(text, template, table); long end1=System.currentTimeMillis(); //获取结束时间 if(pos1 == -1) System.out.println("没有匹配的字符串!"); else System.out.println("存在匹配的字符串,初始位置为:" + pos1); System.out.println("程序运行时间: " + (end1 - start1) + "ms"); System.out.println("------------蛮力法--------------"); long start2=System.currentTimeMillis(); int pos2 = Matching(text, template); long end2=System.currentTimeMillis(); //获取结束时间 if(pos2 == -1) System.out.println("没有匹配的字符串!"); else System.out.println("存在匹配的字符串,初始位置为:" + pos2); System.out.println("程序运行时间: "+(end2 - start2)+"ms"); } }
结果(跑个时间)
原文地址:https://www.cnblogs.com/shish/p/12685731.html
时间: 2024-10-21 12:39:10