[Daily Blue Bridge] 1. "Guess the Age" in the Java Group for the 13th Provincial Games

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Topic: Guess the age

The American mathematician Wiener (N. Wiener) has a premature intelligence and went to university at the age of 11. He was invited to give lectures at Tsinghua University in China in 1935-1936. Once, he attended an important conference and his young face was eye-catching. , So someone asked his age, he replied:

"The cube of my age is a 4 digit number, and the 4th power of my age is a 6 digit number. These 10 digits happen to contain 10 digits from 0 to 9, each of which appears exactly once. Please calculate it. How young was he then,

Directly submit his age number at that time through the browser,

Note: Do not submit the answering process or other explanatory text"

Answer source code:

package 一三年省赛真题;

import java.util.HashSet;
import java.util.Set;
public class One {

	public static void main(String[] args) {
		//在10岁到100岁之间寻找
		for (int i = 10; i < 100; i++) {
			int i3 = i*i*i;	//获取到3次方
			int i4 = i3*i;	//获取到4次方
			String s3 = i3 + "";	
			String s4 = i4 + "";
			
			//判断立方的结果是否是4位数，4次方的结果是否是6位数，字符是否是由10个不重复的数字组成
			//同时成立则输出年龄
			if (s3.length()==4&&s4.length()==6&&check(s3+s4)) {
				System.out.println(i);
			}
		}
	}

	/**
	 * 判断字符是否是由10个不重复的数字组成
	 * @param s 判断的字符
	 * @return true
	 * */
	private static boolean check(String s) {
		Set<Character> set = new HashSet<Character>();	//建立不存放重复字符的集合
//		HashSet<String> set = new HashSet<String>();
		for (int i = 0; i < s.length(); i++) {
			//将字符中的每一个元素单独拿出存放到集合中，若元素重复则不被存放
			set.add(s.charAt(i));	
		}
		return set.size()==10;	//字符长度等于10，返回True
	}
	
}

 

Sample output:

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