A stringSof 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) {
        List<Integer> ans = new ArrayList<>();
        if (S == null || S.length() == 0) return ans;

        int[] lastOccur = new int[26];
        for (int i = 0; i < S.length(); i++){
            lastOccur[S.charAt(i) - 'a'] = i;
        }

        int anchor = 0, j = 0;
        for (int i = 0; i < S.length(); i++){
            j = Math.max(j, lastOccur[S.charAt(i) - 'a']);
            if (i == j){
                ans.add(j - anchor + 1);
                anchor = i + 1;
            }
        }

        return ans;
    }
}