Partition Labels — LeetCode 763 Python Solution

The problem

You are given a string s. We want to partition the string into as many parts as possible so that each letter appears in at most one part.

Example

Input

s = "ababcbacadefegdehijhklij"

Output

[9,7,8]

Explanation

The partition is "ababcbaca", "defegde", "hijhklij".

Python solution

class Solution:
    def partitionLabels(self, s: str) -> List[int]:
        last = {c: i for i, c in enumerate(s)}
        mx = j = 0
        ans = []
        for i, c in enumerate(s):
            mx = max(mx, last[c])
            if mx == i:
                ans.append(i - j + 1)
                j = i + 1
        return ans

Complexity

Pattern: Two Pointers

Use the order already in the input to discard half the search space at every step. LeetCode 763. Partition Labels is filed here because LeetCode tags it Two Pointers, which is the vocabulary this hub collects.

The two pointers guide has the Python template for the pattern and the 201 LeetCode problems that use it.

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