Partition Labels

Description

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.

 

Solution(javascript)

const partitionLabels = (S = '') => {
  const result = []
  const map = {}
  for (let i = 0; i < S.length; i++) {
    map[S[i]] = i
  }
  let start = 0
  while (start <= S.length - 1) {
    let end = map[S[start]]
    for (let i = start + 1; i < end; i++) {
      const currentEnd = map[S[i]]
      if (currentEnd > end) {
        end = currentEnd
      }
    }
    result.push(end - start + 1)
    start = end + 1
  }
  return result
}