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  1. #include <bits/stdc++.h>
  2. using namespace std;
  3.  
  4. #define N	100001
  5. #define L	18	/* L = ceil(log2(N * 2 - 1)) */
  6. #define N_	(1 << L)
  7. #define MD	469762049	/* MD = 56 * 2^23 + 1 */
  8.  
  9. int *wu[L + 1], *wv[L + 1];
  10.  
  11. int power(int a, int k) {
  12. 	long long b = a, p = 1;
  13.  
  14. 	while (k) {
  15. 		if (k & 1)
  16. 			p = p * b % MD;
  17. 		b = b * b % MD;
  18. 		k >>= 1;
  19. 	}
  20. 	return p;
  21. }
  22.  
  23. void init() {
  24. 	int l, i, u, v;
  25.  
  26. 	/* u ^ n must be equal to 1 for FFT */
  27. 	/* since x ^ (MD - 1) = 1 (mod MD) by fermat's little theorem */
  28. 	/* so MD - 1 must be power of 2 as n is a power of 2 */
  29. 	u = power(3, (MD - 1) >> L);
  30.  
  31. 	/* v is u ^ -1 = u ^ (MD - 2) by fermat's little theorem */
  32. 	/* this is for interpolation (inverse FFT) */
  33. 	v = power(u, MD - 2);
  34.  
  35. 	/* find the powers of u and v for each possible n */
  36. 	for (l = L; l > 0; l--) {
  37. 		int n = 1 << (l - 1);
  38.  
  39. 		wu[l] = (int *) malloc(n * sizeof *wu[l]);
  40. 		wv[l] = (int *) malloc(n * sizeof *wv[l]);
  41.  
  42. 		wu[l][0] = wv[l][0] = 1;
  43. 		for (i = 1; i < n; i++) {
  44. 			wu[l][i] = (long long) wu[l][i - 1] * u % MD;
  45. 			wv[l][i] = (long long) wv[l][i - 1] * v % MD;
  46. 		}
  47.  
  48. 		/* change u and for next iteration of n, which becomes n / 2 */
  49. 		/* u ^ n = 1 => (u ^ (n / 2)) ^ 2 = 1 */
  50. 		/* same goes for v */
  51. 		u = (long long) u * u % MD, v = (long long) v * v % MD;
  52. 	}
  53.  
  54. }
  55.  
  56. void ntt_(int *aa, int l, int inverse) {
  57. 	if (l > 0) {
  58. 		int n = 1 << l;
  59. 		int m = n >> 1;
  60. 		int *ww = inverse ? wv[l] : wu[l];
  61.  		int i, j;
  62.  
  63.  		/* solve for even and odd degrees */
  64.  		/* P(x) = P_even(x) + x * P_odd(x) */
  65.  		/* where P_even(x) is the terms with even degree and */
  66.  		/* where P_odd(x) is the terms with odd degree and */
  67. 		ntt_(aa, l - 1, inverse);
  68. 		ntt_(aa + m, l - 1, inverse);
  69.  
  70. 		/* now we make the point value form */
  71. 		for (i = 0; (j = i + m) < n; i++) {
  72.  
  73. 			/* a is even degree */
  74. 			/* b is odd degree, multiply by root^i */
  75. 			/* because we need to multiply back the part from */
  76. 			/* splitting P(x) into P_even(x) + x * P_odd(x) with x = root^i */
  77. 			int a = aa[i];
  78. 			int b = (long long) aa[j] * ww[i] % MD;
  79.  
  80.  			/* even part is all positive for all x of x ^ y */
  81.  			/* odd part is positive for x ^ y such that x is positive (first case, even index) */
  82.  			/* otherwise negative for negative x (second case, odd index) */
  83. 			if ((aa[i] = a + b) >= MD)
  84. 				aa[i] -= MD;
  85. 			if ((aa[j] = a - b) < 0)
  86. 				aa[j] += MD;
  87. 		}
  88. 	}
  89. }
  90.  
  91. void ntt(int *aa, int l, int inverse) {
  92. 	int n_ = 1 << l, i, j;
  93.  
  94. 	/* reverse the bits for each element so that */
  95. 	/* in the FFT we don't have to split the even/odd indexes */
  96. 	/* as it becomes into two ranges: [l, m) and [m, r) */
  97. 	for (i = 0, j = 1; j < n_; j++) {
  98. 		int b;
  99. 		int tmp;
  100.  
  101. 		for (b = n_ >> 1; (i ^= b) < b; b >>= 1)
  102. 			;
  103. 		if (i < j)
  104. 			tmp = aa[i], aa[i] = aa[j], aa[j] = tmp;
  105. 	}
  106. 	ntt_(aa, l, inverse);
  107. }
  108.  
  109. void mult(int *aa, int n, int *bb, int m, int *out) {
  110. 	static int aa_[N_], bb_[N_];
  111. 	int l, n_, i, v;
  112.  
  113. 	/* enlarge size so that it's a power of 2 */
  114. 	l = 0;
  115. 	while (1 << l <= n - 1 + m - 1)
  116. 		l++;
  117. 	n_ = 1 << l;
  118. 	memcpy(aa_, aa, n * sizeof *aa), memset(aa_ + n, 0, (n_ - n) * sizeof *aa_);
  119. 	memcpy(bb_, bb, m * sizeof *bb), memset(bb_ + m, 0, (n_ - m) * sizeof *bb_);
  120.  
  121. 	/* FFT: convert coefficient form to point value form */
  122. 	ntt(aa_, l, 0), ntt(bb_, l,  0);
  123.  
  124. 	/* combine point value forms */
  125. 	for (i = 0; i < n_; i++)
  126. 		out[i] = (long long) aa_[i] * bb_[i] % MD;
  127.  
  128. 	/* Inverse FFT: convert point value form to coefficient form */
  129. 	ntt(out, l, 1);
  130. 	v = power(n_, MD - 2);
  131. 	for (i = 0; i < n_; i++)
  132. 		out[i] = (long long) out[i] * v % MD;
  133. }
  134.  
  135. int main() {
  136. 	static int aa[N], bb[N], out[N_];
  137. 	int n, m, i;
  138.  
  139. 	init();
  140. 	scanf("%d%d", &n, &m), n++, m++;
  141. 	for (i = 0; i < n; i++)
  142. 		scanf("%d", &aa[i]);
  143. 	for (i = 0; i < m; i++)
  144. 		scanf("%d", &bb[i]);
  145. 	mult(aa, n, bb, m, out);
  146. 	for (i = 0; i < n + m - 1; i++)
  147. 		printf("%d ", out[i]);
  148. 	printf("\n");
  149. 	return 0;
  150. }
Runtime error #stdin #stdout #stderr 0.01s 5548KB
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Standard input is empty
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Standard output is empty
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*** buffer overflow detected ***: ./prog terminated
https://ideone.com/mo8ZYw
language:
C++14 (gcc 8.3)
created:
2 years ago
visibility:
public

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