``````A string S of lowercase English letters is given. We want to partition this string into as many parts as possible so that each letter appears in at most one part, and return a list of integers representing the size of these parts.

Example 1:
Output: [9,7,8]
Explanation:
The partition is "ababcbaca", "defegde", "hijhklij".
This is a partition so that each letter appears in at most one part.
A partition like "ababcbacadefegde", "hijhklij" is incorrect, because it splits S into less parts.

Note:
S will have length in range [1, 500].
S will consist of lowercase English letters ('a' to 'z') only.``````

``````class Solution {
public:
vector<int> partitionLabels(string S) {
int last_pos = {0};
int elem_cnt = S.size();
//记录字母最后出现位置
for(int i = 0;i < elem_cnt;i++)
last_pos[S[i]-'a'] = i;

vector<int> res;
int start = 0,last = 0;
for(int i = 0;i < elem_cnt;i++)
{
last = max(last,last_pos[S[i] -'a']);
if(i == last)
{
res.push_back(last - start + 1);
start = last + 1;
}
}

return res;
}
};``````
``````Runtime: 4 ms, faster than 97.63% of C++ online submissions for Partition Labels.
Memory Usage: 6.9 MB, less than 34.09% of C++ online submissions for Partition Labels.``````