不少程序员都会遇到的三个问题

面试问题如下：

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());
    }
}



转自http://www.jfox.info/bu-shao-cheng-xu-yuan-du-hui-peng-dao-de-san-ge-mian-shi-ti