« back

Plus one

Tags : array, leetcode, cpp, easy

Problem Statement - link #

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.

Examples #

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

Example 4:

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 #

Solution #

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