Overview

By scanning the string \(S\) from left to right exactly once and continuously counting how many consecutive Ws there are, we can find the longest winning streak. When an L appears, the streak is broken, so the key point is to reset the count to \(0\).

Analysis

This problem asks us to find the “maximum length of a consecutive W segment.” The important observation is that at each position, all we need is “the current streak length” and “the maximum value so far.”

For example, consider S = "WWLWWWLW":

• W → streak \(1\) (max \(1\))
• W → streak \(2\) (max \(2\))
• L → reset streak to \(0\)
• W → streak \(1\)
• W → streak \(2\)
• W → streak \(3\) (max \(3\))
• L → reset streak to \(0\)
• W → streak \(1\)

The final maximum is \(3\).

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A naive approach of “checking all possible intervals” would be too inefficient due to the large number of intervals (worst case \(O(N^2)\) or more). Since the constraint is \(N \le 10^6\), we need to solve it with a single pass through each character (\(O(N)\)).

The following rules are sufficient for this problem:

• If the character is W, then current += 1
• If the character is L, then current = 0
• Each time, update max_streak = max(max_streak, current)

This way, even when there are no Ws at all, max_streak remains at its initial value of \(0\), giving the correct answer.

Algorithm

1. max_streak = 0 (maximum consecutive wins so far)
2. current = 0 (current consecutive wins)
3. Scan the string \(S\) from left to right:
   • If the character is W, increment current by 1
   • If the character is L, set current to 0
   • Update max_streak with max(max_streak, current)
4. Output max_streak at the end

Complexity

• Time complexity: \(O(N)\)
• Space complexity: \(O(1)\) (excluding the input string)

Implementation Notes

• Don’t forget to set current = 0 when encountering an L.

• Updating max_streak only when the character is W also works correctly (the provided code uses this form).

• Since the input can be large, using sys.stdin.readline in Python ensures stable and fast performance.

  Source Code

import sys

def main():
    input = sys.stdin.readline
    n = int(input().strip())
    s = input().strip()

    max_streak = 0
    current = 0

    for ch in s:
        if ch == 'W':
            current += 1
            if current > max_streak:
                max_streak = current
        else:
            current = 0

    print(max_streak)

if __name__ == "__main__":
    main()

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This editorial was generated by gpt-5.3-codex.