java 面试小问题

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());
    }