试题 B: 不同子串

【问题描述】 一个字符串的非空子串是指字符串中长度至少为 1 的连续的一段字符组成 的串。例如，字符串aaab 有非空子串a, b, aa, ab, aaa, aab, aaab，一共 7 个。 注意在计算时，只算本质不同的串的个数。 请问，字符串0100110001010001 有多少个不同的非空子串？

import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.OutputStreamWriter;
import java.util.HashSet;
import java.util.Scanner;
import java.util.Set;

public class Main {

	static BufferedReader in = new BufferedReader(new InputStreamReader(System.in));
	static BufferedWriter out = new BufferedWriter(new OutputStreamWriter(System.out));

	static Scanner input = new Scanner(System.in);

	public static void main(String[] args) throws IOException {

		String str = input.nextLine();
		String[] s = new String[4000000];
		int k = 0;

		for (int i = 0; i < str.length(); i++) {
			for (int j = i + 1; j <= str.length(); j++) {
				s[k++] = str.substring(i, j);
			}
		}

		Set<String> set = new HashSet<String>();
		for (int i = 0; i < s.length; i++) {
			set.add(s[i]);
		}
		System.out.println(set.size());

	}
}

 

为什么是101而不是100呢  （遍历 的数组aa有个空值也算一个）

看下面这个！@

import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.OutputStreamWriter;
import java.util.HashSet;
import java.util.Scanner;
import java.util.Set;

public class Main {

	static BufferedReader in = new BufferedReader(new InputStreamReader(System.in));
	static BufferedWriter out = new BufferedWriter(new OutputStreamWriter(System.out));

	static Scanner input = new Scanner(System.in);

	public static void main(String[] args) throws IOException {

		String str = "0100110001010001";
		Set<String> set = new HashSet<String>();

		for (int i = 0; i < str.length(); i++) {
			for (int j = i + 1; j <= str.length(); j++) {
				String str1 = str.substring(i, j);
				set.add(str1);
			}
		}

		System.out.println(set.size());

	}
}