BZOJ2179 FFT Fast Fourier

This topic, read the title to know what to do 233

So Konjac Konjac began to learn the FFT ... Then ffting ...

Finally wa3+1ac ...

WA, what's going on?

I'm going to press 4 bits first ... Burst Long long ... Then 3 bits, and a long long T t

So I had to press 2 bits and 233.

1 /**************************************************************2 problem:21793 User:rausen4 language:c++5 result:accepted6 time:616 Ms7 memory:24248 KB8 ****************************************************************/9  Ten#include <cstdio> One#include <cmath> A#include <algorithm> -   - #defineComplex P the using namespacestd; -typedefDoubleLF; -typedefLong Longll; - Const intN =300005; + ConstLF pi = ACOs (-1); -   + structComplex { A lf x, y; at P () {} - P (LF _x, LF _y): X (_x), Y (_y) {} -       -Poperator+ (ConstP &b) { -         returnP (x + b.x, y +b.y); -     } inPoperator- (ConstP &b) { -         returnP (x-b.x, Y-b.y); to     } +Poperator* (ConstP &b) { -         returnP (x * b.x-y * b.y, X * b.y + y *b.x); the     } *} X[n], y[n], w[2][n]; $  Panax Notoginseng intN, K; - ll A[n], b[n]; the   + voidRead (LL *a) { A     intI, now = ceil (LF) n/2) -1; the     CharCH =GetChar (); +      while(Ch <'0'||'9'< ch) ch =GetChar (); -      for(i = n; i;--i) { $(A[now] *=Ten) + = CH-'0'; $CH =GetChar (); -         if(I &1) --Now ; -     } the } -  Wuyi voidPrint (ll *a,intN) { theprintf"%lld", a[n--]); -      for(; ~n;--N) Wuprintf"%02lld", A[n]); - } About   $   - voidFFT (P *x,intKintv) { -     intI, J, L; - P tmp; A      for(i = j =0; I < K; ++i) { +         if(I >j) Swap (X[i], x[j]); the          for(L = k >>1; (J ^= L) < L; L >>=1); -     } $      for(i =2; I <= K; I <<=1) the          for(j =0; J < K; J + =i) the              for(L =0; L < i >>1; ++l) { theTMP = x[j + L + (i >>1)] * w[v][k/i *l]; theX[j + L + (i >>1)] = X[j + L]-tmp; -X[j + L] = x[j + L] +tmp; in             } the } the   About voidWork () { the     inti; the      for(k =1; K < n <<1; K <<=1); the      for(i =0; I <= K; ++i) +w[1][k-i] = w[0][i] = P (cos (pi *2* i/k), sin (pi *2Ik)); -      for(i =0; I < K; ++i) theX[i] = P (A[i],0);BayiFFT (x, K,0); the      for(i =0; I < K; ++i) theY[i] = P (B[i],0); -FFT (Y, K,0); -      for(i =0; I < K; ++i) theX[i] = x[i] *Y[i]; theFFT (x, K,1); the      for(i =0; I <2K ++i) theA[i] = (int) (x[i].x/k +0.5); -      for(i =0; I <2K1; ++i) theA[i +1] + = A[i]/ -, A[i]%= -; the      for(k =2K1;!a[k]; --k); the print (A, k);94 } the   the intMain () { the     inti;98scanf"%d", &n); About Read (a), read (b); -n = ceil (LF) n/2);101 Work ();102     return 0; 103}

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(P.S. Feeling this is a lot simpler and better understood than the Guide = =)

BZOJ2179 FFT Fast Fourier