LeetCode 1221. Split a String in Balanced Strings

Description

https://leetcode.com/problems/split-a-string-in-balanced-strings/

Balanced strings are those that have an equal quantity of 'L' and 'R' characters.

Given a balanced string s, split it in the maximum amount of balanced strings.

Return the maximum amount of split balanced strings.

Example 1:

Input: s = "RLRRLLRLRL"
Output: 4
Explanation: s can be split into "RL", "RRLL", "RL", "RL", each substring contains same number of 'L' and 'R'.

Example 2:

Input: s = "RLLLLRRRLR"
Output: 3
Explanation: s can be split into "RL", "LLLRRR", "LR", each substring contains same number of 'L' and 'R'.

Example 3:

Input: s = "LLLLRRRR"
Output: 1
Explanation: s can be split into "LLLLRRRR".

Example 4:

Input: s = "RLRRRLLRLL"
Output: 2
Explanation: s can be split into "RL", "RRRLLRLL", since each substring contains an equal number of 'L' and 'R'

Constraints:

• 1 <= s.length <= 1000
• s[i] is either 'L' or 'R'.
• s is a balanced string.

Explanation

Two pointers to iterate substring. Whenever encountering a substring with the equal number of “L” and “R”, count it.

Python Solution

class Solution:
    def balancedStringSplit(self, s: str) -> int:
        count = 0
        
        i = 0        
        j = 1
        
        while j <= len(s):
            sub = s[i:j]
            
            if sub.count("R") == sub.count("L"):
                count += 1
                i = j
                j = i + 1
                continue
            
            j += 1
                        
        return count