标签:blog ems += line ++ size org www. tps
分析
注意的地方:
75,76行开始时是这样写的:
memcpy(TA,a,sizeof(int)*(n+1));memset(TA+n+1,0,sizeof(TA)); memcpy(TB,b,sizeof(int)*(m+1));memset(TB+m+1,0,sizeof(TB));
然后开O2的情况不过。最后发现时后面的memset不能这样写。然后在本地开O2测试,可以过样例。。。 ~ 惊!~ 吓!
代码
1 #include<cstdio> 2 #include<algorithm> 3 #include<cstring> 4 #include<cmath> 5 #include<iostream> 6 #include<cctype> 7 8 #define P 998244353 9 #define G 3 10 #define Gi 332748118 11 #define N 270000 12 13 using namespace std; 14 15 int A[N],B[N],D[N],TA[N],TB[N],DR[N],Binv[N],R[N]; 16 17 inline int read() { 18 int x = 0,f = 1;char ch=getchar(); 19 for (; !isdigit(ch); ch=getchar()) if(ch==‘-‘)f=-1; 20 for (; isdigit(ch); ch=getchar()) x=x*10+ch-‘0‘; 21 return x*f; 22 } 23 24 int ksm(int a,int b) { 25 int ans = 1; 26 while (b) { 27 if (b & 1) ans = (1ll * ans * a) % P; 28 a = (1ll * a * a) % P; 29 b >>= 1; 30 } 31 return ans; 32 } 33 void NTT(int *a,int n,int ty) { 34 for (int i=0,j=0; i<n; ++i) { 35 if (i < j) swap(a[i],a[j]); 36 for (int k=(n>>1); (j^=k)<k; k>>=1); 37 } 38 for (int w1,m=2; m<=n; m<<=1) { 39 if (ty == 1) w1 = ksm(G,(P-1)/m); 40 else w1 = ksm(Gi,(P-1)/m); 41 for (int i=0; i<n; i+=m) { 42 int w = 1; 43 for (int k=0; k<(m>>1); ++k) { 44 int u = a[i+k],t = 1ll * w * a[i+k+(m>>1)] % P; 45 a[i+k] = (u + t) % P; 46 a[i+k+(m>>1)] = (u - t + P) % P; 47 w = 1ll * w * w1 % P; 48 } 49 } 50 } 51 if (ty==-1) { 52 int inv = ksm(n,P-2); 53 for (int i=0; i<n; ++i) a[i] = 1ll * a[i] * inv % P; 54 } 55 56 } 57 void Inv(int *A,int *B,int n) { 58 int len = 1; 59 while (len <= n) len <<= 1; 60 B[0] = ksm(A[0],P-2); 61 for (int m=2; m<=len; m<<=1) { 62 for (int i=0; i<m; ++i) TA[i] = A[i],TB[i] = B[i]; 63 NTT(TA,m<<1,1); 64 NTT(TB,m<<1,1); 65 for (int i=0; i<(m<<1); ++i) TA[i] = 1ll*TA[i]*TB[i]%P*TB[i]%P; 66 NTT(TA,m<<1,-1); 67 for (int i=0; i<m; ++i) B[i] = (1ll*2*B[i]%P-TA[i]+P)%P; 68 } 69 memset(TA,0,sizeof(TA)); 70 memset(TB,0,sizeof(TB)); 71 } 72 void Mul(int *a,int *b,int *C,int n,int m) { 73 int len = 1; 74 while (len <= n+m) len <<= 1; 75 for (int i=0; i<=n; ++i) TA[i] = a[i]; 76 for (int i=0; i<=m; ++i) TB[i] = b[i]; 77 NTT(TA,len,1); 78 NTT(TB,len,1); 79 for (int i=0; i<len; ++i) C[i] = (1ll * TA[i] * TB[i]) % P,TA[i] = TB[i] = 0; 80 NTT(C,len,-1); 81 } 82 int main() { 83 int n = read() ,m = read() ; 84 for (int i=0; i<=n; ++i) A[i] = read(); 85 for (int i=0; i<=m; ++i) B[i] = read(); 86 87 reverse(A,A+n+1);reverse(B,B+m+1); 88 89 Inv(B,Binv,n-m); // 求B转换后的逆元 90 Mul(A,Binv,D,n-m,n-m); // 求转换后的D 91 reverse(D,D+n-m+1); 92 for (int i=0; i<=n-m; ++i) printf("%d ",D[i]);puts(""); 93 94 reverse(A,A+n+1);reverse(B,B+m+1); 95 Mul(D,B,R,n-m,m); // 求D*B 96 for (int i=0; i<m; ++i) R[i] = (A[i] - R[i] + P) % P; // 求R 97 for (int i=0; i<m; ++i) printf("%d ",R[i]); 98 99 return 0; 100 }
标签:blog ems += line ++ size org www. tps
原文地址:https://www.cnblogs.com/mjtcn/p/9157378.html