Kayar Pencere

/**
 * Sliding window (variable length), longest valid window.
 * Expand `right`, shrink `left` while the invariant breaks, then record the answer.
 *
 * Minimum covering window: shrink while still valid, update `best` only when valid
 * (often start with `best = Infinity`).
 */
function slidingWindow(s: string): number {
  const freq = new Map<string, number>();
  let left = 0;
  let best = 0;

  const windowOk = () => {
    // Replace with the problem invariant (e.g. all unique, sum ≤ k).
    return true;
  };

  for (let right = 0; right < s.length; right++) {
    // 1) expand: add s[right] into window state
    const add = s[right]!;
    freq.set(add, (freq.get(add) ?? 0) + 1);

    // 2) shrink while the invariant is broken
    while (left <= right && !windowOk()) {
      const rem = s[left]!;
      const next = (freq.get(rem) ?? 0) - 1;
      if (next <= 0) freq.delete(rem);
      else freq.set(rem, next);
      left++;
    }

    // 3) window [left, right] is valid, update answer
    best = Math.max(best, right - left + 1);
  }

  return best;
}

export { slidingWindow };