最长公共子串问题

参考  http://blog.youkuaiyun.com/hackbuteer1/article/details/6686931

public class Test4 {

	static int longest_com_substr(String str1, String str2) {
		int postion = 0,j = 0,len1, len2, len, s1_start = 0, s2_start = 0, curmax = 0, max = 0;
		len1 = str1.length();
		len2 = str2.length();
		len = len1 + len2;
		StringBuilder sb = new StringBuilder();

		char[] str1Array = new char[len1];
		str1Array = str1.toCharArray();
		char[] str2Array = new char[len2];
		str2Array = str2.toCharArray();

		for (int i = 1; i < len; i++) {
			if (i <= len1)
				s1_start = len1 - i;
			else
				s2_start = i - len1;
			curmax = 0;
			for ( j = 0; (s1_start + j < len1) && (s2_start + j < len2); j++) {
				if (str1Array[s1_start + j] == str2Array[s2_start + j]) {
					curmax++;
				} else {
					if (max < curmax) {
						postion  = s1_start+j-1;
						max = curmax;
					}
					curmax = 0;
				}
			}
			if (max < curmax) {
				postion  = s1_start+j-1;
				max = curmax;
			}
		}
		for(int k=0;k<max;k++){
			sb.append(str1Array[postion-max+1+k]);
		}
		System.out.println(sb);
		return max;
	}
	

	public static void main(String[] args) {
		int max;
		max = longest_com_substr("bbbbbba", "qqqqqq");
		System.out.println(max);
	}
}