Code

class Solution {
public:
    vector<int> partitionLabels(string s) {
        int last_pos[26];
        int len = s.size();
        for (int i = 0; i < len; ++i) {
            last_pos[s[i] - 'a'] = i;
        }
        vector<int> ans;
        int start = 0,end = 0;
        for (int i = 0; i < len; ++i) {
            if (end < last_pos[s[i] - 'a']) {
                end = last_pos[s[i] - 'a'];
            }
            if (end == i) {
                ans.emplace_back(end - start + 1);
                start = end + 1;
            }
        }
        return ans;
    }
};