leetcode 806. Number of Lines To Write String

class Solution {
public:
    vector<int> numberOfLines(vector<int>& widths, string S) {
        vector<int> last;
        last.push_back(0);
        last.push_back(0);
        int count=0;
        for(int i=0;i<S.length();i++)
        {
            if(count+widths[S[i]-'a']<=100)count +=widths[S[i]-'a'];
            else
            {
                last[0]++;
                count = widths[S[i]-'a'];
             }
        }
        last[0]++;
        last[1] = count;
        return last;
    }
};