Given a non-negative integer represented as a non-empty array of digits, plus one to the integer.
You may assume the integer do not contain any leading zero, except the number 0 itself.
The digits are stored such that the most significant digit is at the head of the list.
这道题有点偏向数学的感觉，直接上代码：
public class Solution {
public int[] plusOne(int[] digits) {
for(int i = digits.length-1;i>=0;i--){
if(digits[i]>=0&&digits[i]<9){
digits[i]++;
return digits;
}
digits[i]=0;
}
int[] res = new int[digits.length+1];
res[0] = 1;
return res;
}
}