[OJ.leetcode] plus-one

https://oj.leetcode.com/problems/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.

/* digit binaoperation은 언제나 carry 처리/자릿수 변경이 관건 맨 뒷자리부터 1씩 더해나가면서 carry 처리. O(n) carry 관련 문제는 언제나 loop끝나고 남은 carry를 처리해주는 것을 잊지 말것 001 111 101 */ class Solution { public: vector<int> plusOne(vector<int> &digits) { vector<int> res; int carry = 1; //plus one for(vector<int>::reverse_iterator it = digits.rbegin() ; it != digits.rend() ; ++it) { if(*it == 9) { if(carry == 1) { res.push_back(0); carry = 1; } else { res.push_back(9); } } else { res.push_back(*it+carry); carry = 0; } } if(carry == 1) { res.push_back(1); } reverse(res.begin(),res.end()); return res; } };