1 public class Solution {
 2     public int[] plusOne(int[] digits) {
 3        int[] carry=new int[digits.length+1];
 4        int[] results=new int[digits.length+1];
 5        carry[digits.length]=1;
 6        int index=digits.length-1;
 7        for(int i=index; i>=0; i--){
 8            carry[i]=(int)((digits[i]+carry[i+1])/10);
 9            digits[i]=(digits[i]+carry[i+1])%10;
10        }
11        if(carry[0]==0){
12            return digits;
13        }else if(carry[0]==1){
14            for(int k=digits.length-1; k>=0; k--){
15                results[k+1]=digits[k];
16            }
17            results[0]=1;
18        }
19        return results;
20     }
21 }

 1 public class Solution {
 2     public int[] plusOne(int[] digits) {
 3         // Start typing your Java solution below
 4         // DO NOT write main() function    
 5         boolean isNines = true;
 6         for(int i=0;i<digits.length;i++)
 7             if(digits[i]!=9){
 8                 isNines = false;
 9                 break;
10             }
11             
12         if(isNines){
13             int[] result = new int[digits.length+1];
14             result[0] = 1;
15             return result;
16         }
17         
18         int[] result = digits;
19                   
20         int p = result.length-1;
21         int increment=1;
22         
23         while(p>=0 && increment>0){
24             int sum = digits[p]+increment;
25             result[p] = sum%10;
26             increment = sum/10;
27             p--;
28         }
29         return result;
30     }
31 }

 1 public class PlusOne {
 2     public int[] plusOne(int[] digits) {
 3         // Start typing your Java solution below
 4         // DO NOT write main() function
 5         int carry = 1;
 6         int temp;
 7         boolean needMoreDigit = true;
 8         for (int i = digits.length - 1; i >= 0; i--) {
 9             temp = (digits[i] + carry) % 10;
10             // System.out.println("i "+i+"temp "+temp);
11             carry = (digits[i] + carry) / 10;
12             digits[i] = temp;
13             if (carry == 0) {
14                 needMoreDigit = false;
15                 break;
16             }
17         }
18         // System.out.println("nn"+needMoreDigit);
19         if (!needMoreDigit) {
20             return digits;
21         } else {
22             int[] newDigits = new int[digits.length + 1];
23             newDigits[0] = carry;
24             for (int i = 1; i <= digits.length; i++) {
25                 newDigits[i] = digits[i - 1];
26             }
27             return newDigits;
28         }
29 
30     }
31     public static void main(String[] args){
32         PlusOne o = new PlusOne();
33         int[]digits = {9,8,7,6,5,4,3,2,1,0};
34         int[] result = o.plusOne(digits);
35         for(int i=0;i<result.length;i++){
36             System.out.print(" "+result[i]);
37         }
38     }
39 
40 }