Binary Search & Modified BS

def binary_search_on_answer(weights: list[int], days: int) -> int:
    def can_ship(capacity: int) -> bool:
        needed_days = 1
        curr_load = 0
        for w in weights:
            if curr_load + w > capacity:
                needed_days += 1
                curr_load = 0
            curr_load += w
        return needed_days <= days

    # Boundaries: minimum single package and total package weight
    low, high = max(weights), sum(weights)
    best = high
    
    while low <= high:
        mid = low + (high - low) // 2
        if can_ship(mid):
            best = mid        # Capacity works, try to find smaller
            high = mid - 1
        else:
            low = mid + 1     # Capacity too small, must increase
            
    return best