一，求解幸运数
给定一个十进制的数，它的若干位之和等于二进制形式的各个位之和，则它就是幸运数。
比如十进制数123，各个位之和为6；比如十进制数3，各个位之和为3，二进制表示为 011,各个二进制位之和为2 ，这两个和不相等，故十进制数3不是幸运数。
下面程序实现了，给定一个数 num，求 1，2，3，....num 之间的所有的幸运数。
import java.util.Scanner; public class Main { public static void main(String[] args) { Scanner sc = new Scanner(System.in); while(sc.hasNextInt()) { int count = sc.nextInt(); int[] values = new int[count]; for(int i = 0; i < count; i++) { values[i] = sc.nextInt(); } for(int i = 0; i < count; i++) { int res = luckNumbers(values[i]); if(res > 0) System.out.println(res); } } sc.close(); } private static int luckNumbers(int value){ int count = 0; for(int i = 1; i <= value; i++) { int ten = process(i); int binary = process2(i); if(ten == binary) count++; } return count; } private static int process(int value) { int sum = 0; while(value > 0) { sum += value % 10; value = value/10; } return sum; } private static int process2(int num){ int count = 0; for(; num > 0; count++) { num &= (num - 1); } return count; } }
二，第一行
import java.util.Arrays; import java.util.Scanner; public class Main { public static void main(String[] args) { Scanner sc = new Scanner(System.in); while(sc.hasNextLine()) { String line = sc.nextLine(); int tables = Integer.valueOf(line.split(" ")[0]); int customers = Integer.valueOf(line.split(" ")[1]); int[] cap = new int[tables]; line = sc.nextLine(); String lines[] = line.split(" "); for(int i = 0; i < cap.length; i++) cap[i] = Integer.valueOf(lines[i]); Buy[] buyarr = new Buy[customers]; for(int i = 0; i < customers; i++) { line = sc.nextLine(); int numbers = Integer.valueOf(line.split(" ")[0]); int money = Integer.valueOf(line.split(" ")[1]); buyarr[i] = new Buy(money, numbers); } Arrays.sort(cap); Arrays.sort(buyarr); int count = 0; for(int i = 0; i < customers; i++) { int numbers = buyarr[i].numbers; int money = buyarr[i].money; int j = 0; boolean find = false; for(; j < cap.length; j++) if(numbers < cap[j]) { cap[j] = 0; find = true; break; } if(find == true){ count += money; } } System.out.println(count); } } private static class Buy implements Comparable<Buy>{ int money; int numbers; public Buy(int money, int numbers) { this.money = money; this.numbers = numbers; } @Override public int compareTo(Buy o) { return o.money - this.money;//按money从大到小排序 } } }
三，使用两个线程，交替打印 1-10。线程A打印奇数，线程B打印偶数
public class Test{ public static void main(String[] args) { Print p = new Print(); Thread t1 = new ThreadA(p);//负责打印奇数 Thread t2 = new ThreadB(p);//负责打印偶数 t2.start(); try { Thread.sleep(100);//让当前线程睡一会儿，好让t2能够 start } catch (InterruptedException e) { // TODO Auto-generated catch block e.printStackTrace(); } t1.start();//t2 start之后，才启动t1 } } class Print{ private volatile boolean isA = false; public synchronized void printOdd(int i){ try{ while(i <= 9) { while(isA == true) wait(); System.out.print(i); notifyAll();//让t2先启动，由于 isA初始为false,t2会wait，这样 t1获得锁打印了1之后，nofityAll发的通知才不会丢失 i+=2; isA = true; } }catch(InterruptedException e){ e.printStackTrace(); } } public synchronized void print(int i){ try{ while(i <= 10) { while(isA == false) wait(); System.out.print(i); i+=2; notifyAll(); isA = false; } }catch(InterruptedException e){ e.printStackTrace(); } } } class ThreadB extends Thread{ Print p; public ThreadB(Print p) { this.p = p; } @Override public void run() { p.print(2); } } class ThreadA extends Thread{ Print p; public ThreadA(Print p) { this.p = p; } @Override public void run() { p.printOdd(1); } }
