66.plus-one.cpp

/*
 * @lc app=leetcode id=66 lang=cpp
 *
 * [66] Plus One
 *
 * https://leetcode.com/problems/plus-one/description/
 *
 * algorithms
 * Easy (42.14%)
 * Likes:    1444
 * Dislikes: 2305
 * Total Accepted:    585.8K
 * Total Submissions: 1.4M
 * Testcase Example:  '[1,2,3]'
 *
 * Given a non-empty array of digits representing a non-negative integer, plus
 * one to the integer.
 *
 * The digits are stored such that the most significant digit is at the head of
 * the list, and each element in the array contain a single digit.
 *
 * You may assume the integer does not contain any leading zero, except the
 * number 0 itself.
 *
 * Example 1:
 *
 *
 * Input: [1,2,3]
 * Output: [1,2,4]
 * Explanation: The array represents the integer 123.
 *
 *
 * Example 2:
 *
 *
 * Input: [4,3,2,1]
 * Output: [4,3,2,2]
 * Explanation: The array represents the integer 4321.
 *
 */

// @lc code=start
#include <vector>
using std::vector;

class Solution {
   public:
    vector<int> plusOne(vector<int>& digits) {
        int veclen = digits.size();

        for (int i = veclen - 1; i >= 0; i--) {
            if (digits[i] == 9) {
                digits[i] = 0;
            } else {
                digits[i]++;
                return digits;
            }
        }

        digits[0] = 1;
        digits.push_back(0);

        return digits;
    }
};
// @lc code=end