Hat Size Converter

# Hat size conversion table (circumference in cm)
HAT_SIZES = [
    {"cm": 51, "us": "6 3/8", "uk": "6 3/8", "eu": 51},
    {"cm": 52, "us": "6 1/2", "uk": "6 1/2", "eu": 52},
    {"cm": 53, "us": "6 5/8", "uk": "6 5/8", "eu": 53},
    {"cm": 54, "us": "6 3/4", "uk": "6 3/4", "eu": 54},
    {"cm": 55, "us": "6 7/8", "uk": "6 7/8", "eu": 55},
    {"cm": 56, "us": "7",     "uk": "7",     "eu": 56},
    {"cm": 57, "us": "7 1/8", "uk": "7 1/8", "eu": 57},
    {"cm": 58, "us": "7 1/4", "uk": "7 1/4", "eu": 58},
    {"cm": 59, "us": "7 3/8", "uk": "7 3/8", "eu": 59},
    {"cm": 60, "us": "7 1/2", "uk": "7 1/2", "eu": 60},
    {"cm": 61, "us": "7 5/8", "uk": "7 5/8", "eu": 61},
    {"cm": 62, "us": "7 3/4", "uk": "7 3/4", "eu": 62},
    {"cm": 63, "us": "7 7/8", "uk": "7 7/8", "eu": 63},
]

def find_hat_size(cm: float) -> dict | None:
    # Find exact match or nearest
    exact = next((s for s in HAT_SIZES if s["cm"] == int(cm)), None)
    if exact:
        return exact
    # Nearest
    return min(HAT_SIZES, key=lambda s: abs(s["cm"] - cm))

# Convert cm to US/UK/EU sizes
result = find_hat_size(57)
print(f"Head circumference: {result['cm']} cm")
print(f"US size:  {result['us']}")
print(f"UK size:  {result['uk']}")
print(f"EU size:  {result['eu']}")