[LC] 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 List<Integer> partitionLabels(String S) {
        Map<Character, Integer> map = new HashMap<>();
        for (int i = 0; i < S.length(); i++) {
            map.put(S.charAt(i), i);
        }
        
        int lastIndex = 0;
        int start = 0, i = 0;
        List<Integer> list = new ArrayList<>();
        while (i < S.length()) {
            lastIndex = Math.max(lastIndex, map.get(S.charAt(i)));
            // current index get to farest up to now
            if (i == lastIndex) {
                list.add(lastIndex - start + 1);
                start = lastIndex + 1;
            }
            i += 1;
        }
        return list;
    }
}