用递归打印数字

题目

解题

public List<Integer> numbersByRecursion(int n) {
// write your code here
List<Integer> result = new ArrayList<Integer>();
int Max = (int)Math.pow(10,n);
for(int i=1;i< Max;i++)
result.add(i);
return result;

}

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> result = new ArrayList<Integer>();
if(n<=0)
return result;
PrintN(n,result);
return result;

}
public int PrintN(int n,List<Integer> res){
if(n==0){
return 1;
}
int base = PrintN(n-1,res);
int size = res.size();
for(int i = 1;i<= 9;i++){
int subbase = base*i;
res.add(subbase);
for(int j= 0;j< size ;j++){
res.add(subbase+res.get(j));
}
}
return base*10;
}
}