leetcode 066 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.

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/*class Solution {
public:
vector<int> plusOne(vector<int> &digits) {
vector<int> ret;
int len = digits.size();
int cnt=0;

for(int i=len-1; i >= 0; i--) {
int sum = digits[i]+cnt;
cnt = sum/10;
sum = sum%10;

ret.push_back(sum);
}

if(cnt > 0) ret.push_back(cnt);

reverse(ret.begin(), ret.end());
return ret;
}
}*/

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]=0;
} else {
digits[i]++;
return digits;
}
}

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