Max Chunks To Make Sorted II — LeetCode 768 Python Solution

The problem

You are given an integer array arr. We split arr into some number of chunks (i.e., partitions), and individually sort each chunk.

Example

Input

arr = [5,4,3,2,1]

Output

1

Explanation

Splitting into two or more chunks will not return the required result.

Python solution

class Solution:
    def maxChunksToSorted(self, arr: List[int]) -> int:
        stk = []
        for v in arr:
            if not stk or v >= stk[-1]:
                stk.append(v)
            else:
                mx = stk.pop()
                while stk and stk[-1] > v:
                    stk.pop()
                stk.append(mx)
        return len(stk)

Complexity

Pattern: Stack

When the most recent unresolved thing is the one that matters, use a stack. LeetCode 768. Max Chunks To Make Sorted II is filed here because LeetCode tags it Stack, which is the vocabulary this hub collects.

The stack guide has the Python template for the pattern and the 194 LeetCode problems that use it.

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