LeetCode刷题【剑指 Offer 17】打印从1到最大的n位数

输入: n = 1
输出: [1,2,3,4,5,6,7,8,9]

打表
简单打表

class Solution {
    final static int [] sizeTable = { 9, 99, 999, 9999, 99999, 999999, 9999999,
            99999999, 999999999, Integer.MAX_VALUE };
    public int[] printNumbers(int n) {
        int max = sizeTable[n-1];
        int[] arr = new int[max];
        int i = -1;
        while (++i < max){
            arr[i] = i + 1;
        }
        return arr;
    }
}

这个sizeTable在java基础类库java.lang.Integer中就有，挺好用的

    final static int [] sizeTable = { 9, 99, 999, 9999, 99999, 999999, 9999999,
                                      99999999, 999999999, Integer.MAX_VALUE };

    // Requires positive x
    static int stringSize(int x) {
        for (int i=0; ; i++)
            if (x <= sizeTable[i])
                return i+1;
    }