Make The String Great — LeetCode 1544 Python Solution

The problem

Given a string s of lower and upper case English letters. A good string is a string which doesn't have two adjacent characters s[i] and s[i + 1] where: 0 <= i <= s.length - 2 s[i] is a lower-case letter and s[i + 1] is the same letter but in upper-case or vice-versa.

Example

Input

s = "leEeetcode"

Output

"leetcode"

Explanation

In the first step, either you choose i = 1 or i = 2, both will result "leEeetcode" to be reduced to "leetcode".

Python solution

class Solution:
    def makeGood(self, s: str) -> str:
        stk = []
        for c in s:
            if not stk or abs(ord(stk[-1]) - ord(c)) != 32:
                stk.append(c)
            else:
                stk.pop()
        return "".join(stk)

Complexity

Pattern: Stack

When the most recent unresolved thing is the one that matters, use a stack. LeetCode 1544. Make The String Great is filed here on both counts: the reference solution below belongs to the algorithm family this hub collects, and LeetCode tags it Stack.

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

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