2017.1.30 Java有感3.1

1. 求从10到100中能被3或5整除的数的和
int sum = 0; 

for(int i = 10; i <= 100; i++)

 if( i % 3 == 0 || i % 5 == 0)

 sum += i;

 System.out.println(sum);

2. 将一个字符串逆序，不要使用反转函数
String message = \"he saw a racecar\"; 

StringBuilder rev = new StringBuilder(); 

for(int i = message.length()-1; i >= 0; i--) rev.append(message.charAt(i));

System.out.println(rev.toString());

3. 反转一个栈

import java.util.*;

public class MyProgram extends com.ktbyte.submit.Coder {

    public static void main(String[] args) {

        Stack items = new Stack();

        items.push(\"he\");      //he is at the bottom of the stack

        items.push(\"saw\");

        items.push(\"a\");

        items.push(\"racecar\");

        reverseStack(items);   //now he is at the top

        //print in order pushed:

        while(items.size()>0) System.out.println(items.pop());

    }

    public static  void reverseStack(Stack stack) {

        Queue rev = new LinkedList();

        while(stack.size()>0) rev.offer(stack.pop());

        while(rev.size()>0)   stack.push(rev.poll());

    }

}