[LintCode]Print Numbers by Recursion

http://www.lintcode.com/en/problem/print-numbers-by-recursion/

递归打印1 ~ n，n可能很大，要防止栈溢出

public class Solution {    /**     * @param n: An integer.     * return : An array storing 1 to the largest number with n digits.     */    public List<Integer> numbersByRecursion(int n) {        // write your code here        List<Integer> res = new ArrayList();        recursive(n, 0, res);        return res;    }    private void recursive(int n, int ans, List<Integer> res) {        if (n == 0) {            // 保证第一个0不出现            if (ans > 0) {                res.add(ans);            }            return;        }        for (int i = 0; i < 10; i++) {            recursive(n - 1, ans * 10 + i, res);        }    }}