字符串包含-Sunday算法

Sunday算法

判断字符串是否包含特定子串的算法，实现简单，运行高效。

import java.util.HashMap;
import java.util.Map;

public class Sunday {

    public static void main(String[] args) {
        System.out.println(contain("BBC ABCDAB ABCDABCDABDE","ABCDABD"));

    }

    public static int contain(String sourse,String target){
        char[] sou = sourse.toCharArray();
        char[] tar  = target.toCharArray();
        int S = sou.length;
        int T = tar.length;

        Map<Character,Integer> map = new HashMap<Character,Integer>();
        for(int i =0;i<tar.length;i++) {
            map.put(tar[i],i);
        }

        int s =0;
        int t =0;
        while(s<=S-T) {
            t=0;
            while(sou[s+t]==tar[t]) {
                t++;
                if(t>T-1) {
                    return s;
                }
            }
            if(map.containsKey(sou[s+T+1])) {
                s+=T+1-map.get(sou[s+T+1]);
            }else {
                s+=T+1;
            }
        }
        return -1;
    }
}