763. Partition Labels

A string S of lowercase 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:

Input: S = "ababcbacadefegdehijhklij"
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:

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

class Solution {
public:
    vector partitionLabels(string S) {
        vector res;
        unordered_map tmp;
        //找到每个字母出现的最后位置
        for(int i=0;i             tmp[S[i]]=i;
        //开始从头切分，找到第一个字母出现的最长距离
        int low=0;
        int high=INT_MAX;
        while(low!=S.length()){
            //找到第一个字母出现的最长距离
            high=tmp[S[low]];
            //在这段长度中找寻是否有更长的地方
            for(int i=low;i                 high=max(tmp[S[i]],high);
            }
            //找到最大切分长度
            res.push_back(high-low+1);

            //继续切分剩余字符串，更新开头
            low=high+1;
        }
        //返回结果
        return res;
    }
};