66. Plus One

 1 class Solution {
 2     public int[] plusOne(int[] digits) {
 3         int n = digits.length;
 4         int[] res = new int[n+1];
 5         int carry = 0;
 6         for(int i = n - 1; i >= 0; i--) {
 7             if(i == n - 1) {
 8                 carry = (digits[i]+1) / 10;  //digits 会被覆盖 所以先记录carry
 9                 digits[i] = (digits[i]+1) % 10;
10                 
11             }else {
12                 int tmp = digits[i];  //digits 会被覆盖 所以先记录
13                 digits[i] = (digits[i]+carry) % 10;
14                 carry = (tmp+carry) / 10;
15             }
16             
17             if(i == 0 && carry == 1) {
18                 res[0] = 1;
19                 for(int j = 1; j < n+1; j++) {
20                     res[j] = digits[j-1];
21                 }
22                 return res;
23             }            
24         }
25         return digits;
26     }
27 }