763. Partition Labels --------M ~~~

 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:

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:

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

A:

挺好的题。 就是每次找到最右边。

class Solution {
public:
    vector<int> partitionLabels(string S) {
        int n = S.length();
        unordered_map<char, int> M;
        for(int i =0;i<n;i++){
            M[S[i]] = i;
        }
        vector<int> res;
        int start = 0;
        while(start < n){            
            int end = M[S[start]];
            for(int i =start;i<=end;i++){
                end = max(end, M[S[i]]);
            }
            res.push_back(end-start+1);
            start = end+1;
        }
        return res;
    }
};