"Randomization algorithm" Codeforces Matrix God

http://codeforces.com/gym/101341

Test instructions

• Given three square a,b,c, Q Ab=c is it set up?
• The scale of the square is up to 1000.

Ideas

• The time complexity for AB is n*n*n and will time out
• Left multiply by one row n column vector, time complexity reduced to n*n

"Accepted"

1#include <iostream>2#include <cstdio>3#include <cstring>4#include <string>5#include <algorithm>6#include <cmath>7#include <queue>8 9 using namespacestd;TentypedefLong Longll; One Const intinf=0x3f3f3f3f; A Const intmaxn=1e3+2; - Constll mod=1e9+7; -ll a[maxn][maxn],b[maxn][maxn],c[maxn][maxn],r[2][maxn],ra[2][maxn],rab[2][maxn],rc[2][MAXN]; the intn,m; -  - intMain () - { +      while(~SCANF ("%d",&N)) -     { +          for(intI=1; i<=n;i++) A         { at              for(intk=1; k<=n;k++) -             { -scanf"%lld",&a[i][k]); -             } -          }  -          for(intI=1; i<=n;i++) in         { -              for(intk=1; k<=n;k++) to             { +scanf"%lld",&b[i][k]); -             } the          }  *          for(intI=1; i<=n;i++) $         {Panax Notoginseng              for(intk=1; k<=n;k++) -             { thescanf"%lld",&c[i][k]); +             } A          }  the          for(intI=1; i<=n;i++) +         { -r[1][i]=rand ()% -+1; $         } $memset (RA,0,sizeof(RA)); -Memset (Rab,0,sizeof(RAB)); -          for(intI=1; i<=n;i++) the         { -              for(intk=1; k<=n;k++)Wuyi             { thera[1][i]= (ra[1][i]+r[1][K]*A[K][I]%MOD)%MoD; -             } Wu         } -          for(intI=1; i<=n;i++) About         { $              for(intk=1; k<=n;k++) -             { -rab[1][i]= (rab[1][i]+ra[1][K]*B[K][I]%MOD)%MoD; -             } A         } +          for(intI=1; i<=n;i++) the         { -              for(intk=1; k<=n;k++) $             { therc[1][i]= (rc[1][i]+r[1][K]*C[K][I]%MOD)%MoD; the             } the         } the         intflag=1; -          for(intI=1; i<=n;i++) in         { the             if(rab[1][i]!=rc[1][i]) the             {     Aboutflag=0; the                  Break; the             } the         } +         if(flag) -         { thePuts"YES");Bayi         } the         Else the         { -Puts"NO"); -         } the          the     }     the     return 0; the}

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"Randomization algorithm" Codeforces Matrix God