LeetCode66. Plus One

一、题目

You are given a large integer represented as an integer array digits, where each digits[i] is the ith digit of the integer. The digits are ordered from most significant to least significant in left-to-right order. The large integer does not contain any leading 0’s.

Increment the large integer by one and return the resulting array of digits.

Example 1:

Input: digits = [1,2,3]
Output: [1,2,4]
Explanation: The array represents the integer 123.
Incrementing by one gives 123 + 1 = 124.
Thus, the result should be [1,2,4].
Example 2:

Input: digits = [4,3,2,1]
Output: [4,3,2,2]
Explanation: The array represents the integer 4321.
Incrementing by one gives 4321 + 1 = 4322.
Thus, the result should be [4,3,2,2].
Example 3:

Input: digits = [9]
Output: [1,0]
Explanation: The array represents the integer 9.
Incrementing by one gives 9 + 1 = 10.
Thus, the result should be [1,0].

Constraints:

1 <= digits.length <= 100
0 <= digits[i] <= 9
digits does not contain any leading 0’s.

二、题解

class Solution {
   
public:
    vector<int> plusOne(vector<int>& digits) {
   
        int n = digits.size();
        for(int i = n - 1;i >= 0;i--){
   
            if(digits[i] != 9){
   
                digits[i]++;
                for(int j = i + 1;j < n;j++){
   
                    digits[j] = 0;
                }
                return digits;
            }
        }
        vector<int> res(n+1,0);
        res[0] = 1;
        return res;
    }
};