考试结束前5、6min的时候想到……但是写挂了QAQ
其实就是(差值最大的逆序对之差+1)/2;
找逆序对其实维护一个max直接往过扫就可以了……因为逆序对是前面的数大于后面的数……
正确性显然？就是蛮显然的啊= =
1 /************************************************************** 2 Problem: 3613 3 User: Tunix 4 Language: C++ 5 Result: Accepted 6 Time:6136 ms 7 Memory:1272 kb 8 ****************************************************************/ 9 10 //Huce #6 D 11 #include<vector> 12 #include<cstdio> 13 #include<cstdlib> 14 #include<cstring> 15 #include<iostream> 16 #include<algorithm> 17 #define rep(i,n) for(int i=0;i<n;++i) 18 #define F(i,j,n) for(int i=j;i<=n;++i) 19 #define D(i,j,n) for(int i=j;i>=n;--i) 20 using namespace std; 21 22 int getint(){ 23 int v=0,sign=1; char ch=getchar(); 24 while(ch<'0'||ch>'9') {if (ch=='-') sign=-1; ch=getchar();} 25 while(ch>='0'&&ch<='9') {v=v*10+ch-'0'; ch=getchar();} 26 return v*sign; 27 } 28 typedef long long LL; 29 const int N=5000010,INF=~0u>>2; 30 /*******************tamplate********************/ 31 LL n,sa,sb,sc,sd,a[3],MOD; 32 inline LL Fx(int x){ 33 return (sa*x%MOD *x%MOD*x%MOD+sb*x%MOD*x%MOD+sc*x%MOD+sd)%MOD; 34 } 35 36 int main(){ 37 #ifndef ONLINE_JUDGE 38 freopen("D.in","r",stdin); 39 // freopen("output.txt","w",stdout); 40 #endif 41 n=getint(); sa=getint(); sb=getint(); sc=getint(); 42 sd=getint(); a[1]=getint(); MOD=getint(); 43 LL mx=a[1],ans=0; 44 F(i,2,n){ 45 a[i%3]=(Fx(a[(i-1)%3])+Fx(a[(i-2)%3]))%MOD; 46 ans=max(mx-a[i%3],ans); 47 mx=max(mx,a[i%3]); 48 } 49 printf("%d\n",(ans+1)/2); 50 return 0; 51 }