[leetCode]763. 划分字母区间

贪心算法+双指针

class Solution {
    public List<Integer> partitionLabels(String S) {
        // 字符串S中每个字母最后出现的下标
        int[] last = new int[26];
        int length = S.length();
        for (int i = 0; i < length; i++) {
            last[S.charAt(i) - 'a'] = i;
        }
        // 遍历字符串
        int start = 0, end = 0;
        List<Integer> partitions = new ArrayList<>();
        for (int i = 0; i < length; i++) {
            end = Math.max(end,last[S.charAt(i) - 'a']);
            if (i == end) {
                partitions.add(end - start + 1);
                start = end + 1;
            }
        }
        return partitions;
    }
}