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BruteForce.java
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BruteForce.java
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package algorithm.string;
/**
* @author roseduan[roseduan520@gmail.com]
* @time 2019/12/28 15:01
* @description BF算法,暴力匹配
*/
public class BruteForce {
/**
* 第一种写法
* @param main 主串
* @param ptn 模式串
* @return 结果
*/
public static int bf1(String main, String ptn){
int n = main.length();
int m = ptn.length();
if (m > n){
return -1;
}
for (int i = 0; i <= n - m; i++) {
for (int j = 0; j < m; j++) {
if (main.charAt(i + j) != ptn.charAt(j)){
break;
}
if (j == m - 1){
return i;
}
}
}
return -1;
}
/**
* 第二种写法
* @param main 主串
* @param ptn 模式串
* @return 结果
*/
public static int bf2(String main, String ptn){
int n = main.length();
int m = ptn.length();
if (m > n){
return -1;
}
for (int i = 0; i <= n - m; i++) {
int p = i;
int q = 0;
while (main.charAt(p++) == ptn.charAt(q++)){
if (q == m){
return i;
}
}
}
return -1;
}
}