oj.uz

Submission #741218

# Submission time Handle Problem Language Result Execution time Memory
741218 2023-05-13T21:13:52 Z rainboy Multiply (CEOI17_mul) C
100 / 100
 31 ms 2892 KB 
#include <stdio.h>
#include <stdlib.h>

#define N	50000
#define M	50000
#define L	17	/* L = ceil(log2(N + M)) */
#define N_	(1 << L)
#define MD	998244353

long long power(long long a, int k) {
	long long p = 1;

	while (k) {
		if (k & 1)
			p = p * a % MD;
		a = a * a % MD;
		k >>= 1;
	}
	return p;
}

int *wwu[L + 1], *wwv[L + 1], vv_[L + 1];

void init() {
	int l, u, v;

	u = power(3, MD - 1 >> L), v = power(u, MD - 2);
	for (l = L; l > 0; l--) {
		int n = 1 << l, m = n >> 1, i;

		vv_[l] = power(n, MD - 2);
		wwu[l] = (int *) malloc(m * sizeof *wwu[l]);
		wwv[l] = (int *) malloc(m * sizeof *wwv[l]);
		wwu[l][0] = wwv[l][0] = 1;
		for (i = 1; i < m; i++) {
			wwu[l][i] = (long long) wwu[l][i - 1] * u % MD;
			wwv[l][i] = (long long) wwv[l][i - 1] * v % MD;
		}
		u = (long long) u * u % MD, v = (long long) v * v % MD;
	}
	vv_[0] = 1;
}

void ntt_(int *aa, int l, int inverse) {
	if (l) {
		int n = 1 << l, m = n >> 1, *ww = inverse ? wwv[l] : wwu[l], i, j;

		ntt_(aa, l - 1, inverse), ntt_(aa + m, l - 1, inverse);
		for (i = 0; (j = i + m) < n; i++) {
			int a = aa[i], b = (long long) aa[j] * ww[i] % MD;

			if ((aa[i] = a + b) >= MD)
				aa[i] -= MD;
			if ((aa[j] = a - b) < 0)
				aa[j] += MD;
		}
	}
}

void ntt(int *aa, int l, int inverse) {
	int n = 1 << l, i, j;

	for (i = 0, j = 1; j < n; j++) {
		int m = n >> 1, tmp;

		while ((i ^= m) < m)
			m >>= 1;
		if (i < j)
			tmp = aa[i], aa[i] = aa[j], aa[j] = tmp;
	}
	ntt_(aa, l, inverse);
}

int main() {
	static char aa[N + 1], bb[M + 1];
	static int aa_[N_], bb_[N_], cc[N + M];
	int n, m, n_, l_, i, j;

	init();
	scanf("%d%d%s%s", &n, &m, aa, bb);
	for (i = 0; i < n; i++)
		aa_[i] = aa[n - 1 - i] - '0';
	for (j = 0; j < m; j++)
		bb_[j] = bb[m - 1 - j] - '0';
	l_ = 0;
	while (1 << l_ < n + m)
		l_++;
	n_ = 1 << l_;
	ntt(aa_, l_, 0), ntt(bb_, l_, 0);
	for (i = 0; i < n_; i++)
		aa_[i] = (long long) aa_[i] * bb_[i] % MD;
	ntt(aa_, l_, 1);
	for (i = 0; i < n_; i++)
		aa_[i] = (long long) aa_[i] * vv_[l_] % MD;
	for (i = 0; i + 1 < n + m; i++) {
		cc[i] += aa_[i];
		cc[i + 1] += cc[i] / 10, cc[i] %= 10;
	}
	i = n + m - 1;
	while (i > 0 && cc[i] == 0)
		i--;
	while (i >= 0)
		printf("%d", cc[i--]);
	printf("\n");
	return 0;
}

Compilation message

mul.c: In function 'init':
mul.c:27:22: warning: suggest parentheses around '-' inside '>>' [-Wparentheses]
   27 |  u = power(3, MD - 1 >> L), v = power(u, MD - 2);
      |                      ^~
mul.c: In function 'main':
mul.c:80:2: warning: ignoring return value of 'scanf' declared with attribute 'warn_unused_result' [-Wunused-result]
   80 |  scanf("%d%d%s%s", &n, &m, aa, bb);
      |  ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Subtask #1
20.0 / 20.0

# Verdict Execution time Memory Grader output
1 Correct 2 ms 1236 KB Output is correct
2 Correct 2 ms 1364 KB Output is correct
3 Correct 2 ms 1344 KB Output is correct
4 Correct 2 ms 1364 KB Output is correct
5 Correct 2 ms 1364 KB Output is correct

Subtask #2
20.0 / 20.0

# Verdict Execution time Memory Grader output
1 Correct 2 ms 1236 KB Output is correct
2 Correct 2 ms 1364 KB Output is correct
3 Correct 2 ms 1344 KB Output is correct
4 Correct 2 ms 1364 KB Output is correct
5 Correct 2 ms 1364 KB Output is correct
6 Correct 2 ms 1348 KB Output is correct
7 Correct 1 ms 1236 KB Output is correct
8 Correct 1 ms 1344 KB Output is correct
9 Correct 2 ms 1364 KB Output is correct
10 Correct 2 ms 1364 KB Output is correct

Subtask #3
30.0 / 30.0

# Verdict Execution time Memory Grader output
1 Correct 2 ms 1236 KB Output is correct
2 Correct 2 ms 1364 KB Output is correct
3 Correct 2 ms 1344 KB Output is correct
4 Correct 2 ms 1364 KB Output is correct
5 Correct 2 ms 1364 KB Output is correct
6 Correct 2 ms 1348 KB Output is correct
7 Correct 1 ms 1236 KB Output is correct
8 Correct 1 ms 1344 KB Output is correct
9 Correct 2 ms 1364 KB Output is correct
10 Correct 2 ms 1364 KB Output is correct
11 Correct 3 ms 1492 KB Output is correct
12 Correct 3 ms 1364 KB Output is correct
13 Correct 3 ms 1364 KB Output is correct
14 Correct 4 ms 1492 KB Output is correct
15 Correct 3 ms 1364 KB Output is correct

Subtask #4
30.0 / 30.0

# Verdict Execution time Memory Grader output
1 Correct 2 ms 1236 KB Output is correct
2 Correct 2 ms 1364 KB Output is correct
3 Correct 2 ms 1344 KB Output is correct
4 Correct 2 ms 1364 KB Output is correct
5 Correct 2 ms 1364 KB Output is correct
6 Correct 2 ms 1348 KB Output is correct
7 Correct 1 ms 1236 KB Output is correct
8 Correct 1 ms 1344 KB Output is correct
9 Correct 2 ms 1364 KB Output is correct
10 Correct 2 ms 1364 KB Output is correct
11 Correct 3 ms 1492 KB Output is correct
12 Correct 3 ms 1364 KB Output is correct
13 Correct 3 ms 1364 KB Output is correct
14 Correct 4 ms 1492 KB Output is correct
15 Correct 3 ms 1364 KB Output is correct
16 Correct 15 ms 2132 KB Output is correct
17 Correct 31 ms 2892 KB Output is correct
18 Correct 13 ms 2132 KB Output is correct
19 Correct 24 ms 2788 KB Output is correct
20 Correct 9 ms 2004 KB Output is correct