[leetcode]Plus One

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Plus One

Given a non-negative number represented as an array of digits, plus one to the number.

The digits are stored such that the most significant digit is at the head of the list.

演算法思路：

只有當該數組元素全是9的時候才產生進位，即：每一個元素都產生進位，一直到第0個元素還產生進位的時候，數組才需要擴充。一旦遇到哪個元素不需要進位，則返回結果。

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