def comb(self, k):
assert self.n < Mint.MOD
if k < 0 or k > self.n:
return Mint(0)
if k == 0 or k == self.n:
return Mint(1)
return self.fact[self.n] * self.ifact[k] * self.ifact[self.n - k]
def __init__(self, n):
self.n = n
self.fact = [Mint(1)] * (n + 1)
self.ifact = [Mint(1)] * (n + 1)
for i in range(1, n + 1):
self.fact[i] = self.fact[i - 1] * Mint(i)
self.ifact[n] = self.fact[n].inv()
for i in range(n, 0, -1):
self.ifact[i - 1] = self.ifact[i] * Mint(i)
def comb(self, n, k):
assert n < Mint.MOD
if k < 0 or k > n:
return Mint(0)
if k == 0 or k == n:
return Mint(1)
numerator = Mint(n-k+1)
for i in range(n-k+2, n+1):
numerator *= Mint(i)
d = Mint(1)
for i in range(2, k+1):
d *= Mint(i)
denominator = d.inv()
return numerator*denominator
def test_sub_2(self):
a = Mint(self.TEN * 2)
b = Mint(self.TEN)
ans = a - b
exp = self.TEN % self.MOD
self.assertEqual(exp, ans.x)
def test_sub(self):
a = Mint(4)
b = Mint(2)
ans = a - b
self.assertEqual(2, ans.x)
def test_add_2(self):
a = Mint(self.TEN)
b = Mint(self.TEN)
ans = a + b
exp = (self.TEN % self.MOD + self.TEN % self.MOD) % self.MOD
self.assertEqual(exp, ans.x)
def test_add(self):
a = Mint(2)
b = Mint(2)
ans = a + b
self.assertEqual(4, ans.x)
self.assertEqual(2, a.x)
def test_pow_2(self):
a = Mint(self.TEN)
n = 2
ans = a**n
exp = 10**20 % self.MOD
self.assertEqual(exp, ans.x)
def test_pow(self):
a = Mint(2)
n = 10
ans = a**n
self.assertEqual(2**10, ans.x)
def test_isub(self):
ans = Mint(10)
ans -= Mint(2)
self.assertEqual(8, ans.x)
def test_iadd_2(self):
ans = Mint(self.TEN)
ans += Mint(self.TEN)
exp = (self.TEN % self.MOD + self.TEN % self.MOD) % self.MOD
self.assertEqual(exp, ans.x)
def test_iadd(self):
ans = Mint(4)
ans += Mint(4)
self.assertEqual(8, ans.x)
def test_div_2(self):
a = Mint(self.TEN * 2)
b = Mint(self.TEN)
ans = a // b
self.assertEqual(2, ans.x)
def test_div(self):
a = Mint(4)
b = Mint(2)
ans = a // b
self.assertEqual(2, ans.x)
def test_idiv_2(self):
ans = Mint(self.TEN)
ans //= Mint(2)
self.assertEqual((self.TEN // 2) % self.MOD, ans.x)
def test_mul(self):
a = Mint(4)
b = Mint(2)
ans = a * b
self.assertEqual(8, ans.x)
def test_mul_2(self):
a = Mint(self.TEN)
b = Mint(self.TEN)
ans = a * b
exp = 10**20 % self.MOD
self.assertEqual(exp, ans.x)
def test_isub_2(self):
ans = Mint(self.TEN * 2)
ans -= Mint(self.TEN)
exp = self.TEN % self.MOD
self.assertEqual(exp, ans.x)
def test_init(self):
ans = Mint(self.TEN)
self.assertEqual(self.TEN % self.MOD, ans.x)
def test_imul(self):
ans = Mint(10)
ans *= Mint(2)
self.assertEqual(20, ans.x)
def test_idiv(self):
ans = Mint(10)
ans //= Mint(2)
self.assertEqual(5, ans.x)
def test_imul_2(self):
ans = Mint(self.TEN)
ans *= Mint(self.TEN)
exp = (10**20) % self.MOD
self.assertEqual(exp, ans.x)
