CF 379D NewYearLetter [dp+暴力]

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题意：

给出k,x,n,m

找出这样的字符串s1,s2,s1长为n,s2长为m

给出规则，sn=sn-1+sn-2

使得第Sk项出现x个"AC"子串

我们很容易知道k次运算后有几个12，几个21，几个22子串，有几个串1，有几个串2

如果我们知道s1中出现了几个AC，s2中出现了几个AC

s1头和尾，s2头和尾巴

我们就能算出k次后能出现几个AC

现在正好反过来，我们都不知道s1,s2，我们要找出这样的s1,s2

那么我们枚举

s1头和尾，s2头和尾巴

s1中出现了几个AC，s2中出现了几个AC

算出来的Sk里面出现的AC数和x是否相等

直到枚举出来这样的

没有的话就输出happy new year

#include <cstdio>#include <cstring>#include <cmath>#include <iostream>#include <algorithm>using namespace std;long long k,x,n,m;long long lastnum[4][4];long long num[4][4];long long x1=1,x2=0;long long xx1=0,xx2=1;long long tmp[4][4];void copy(long long to[][4],long long from[][4]){for(long long i=1;i<=2;i++)for(long long j=1;j<=2;j++)to[i][j]=from[i][j];}void add(long long to[][4],long long from[][4]){for(long long i=1;i<=2;i++)for(long long j=1;j<=2;j++)to[i][j]+=from[i][j];}long long ac_num(char* s){long long cnt=0;long long len=strlen(s);for(long long i=0;i<len;i++)if(s[i]=='A' && s[i]=='C') cnt++;return cnt;}bool can(long long num1,long long num2,long long suf1,long long suf2,long long pre1,long long pre2){if(xx1*num1+xx2*num2+num[1][2]*(suf1=='A' && pre2=='C')+num[2][2]*(suf2=='A' && pre2=='C')+num[2][1]*(suf2=='A' && pre1=='C')==x){///cout<<"n::"<<num[1][2]<<' '<<num[2][2]<<' '<<num[2][1]<<endl;return true;}elsereturn false;}bool print(long long num1,long long num2, char suf1,char suf2,char pre1,char pre2){        if(n==1 && pre1 != suf1) return false;        if(m==1 && pre2 != suf2) return false;if(n%2==0){ if(num1==n/2) if(!(suf1=='C' && pre1=='A')) return false;}else if(num1==n/2)if ((!(pre1=='A'||suf1=='C'))&&(n!=1))return false;if(m%2==0){ if(num2==m/2) if(!(suf2=='C' && pre2=='A')) return false;}else if(num2==m/2) if ((!(pre2=='A'||suf2=='C'))&&(m!=1)) return false;if(n%2==0){if(num1==n/2){for(long long i=1;i<=num1;i++)cout<<"AC";}else{cout<<pre1;for(long long i=1;i<=num1;i++)cout<<"AC";for(long long i=1;i<=n-num1*2-2;i++)cout<<"B";cout<<suf1;}}else{if(num1==n/2){            if(n==1) cout<<pre1;else                if(pre1=='A'){                    for(long long i=1;i<=num1;i++)cout<<"AC";                    cout<<suf1;                }else if(suf1=='C'){                    cout<<pre1;                    for(long long i=1;i<=num1;i++)cout<<"AC";                }}else{cout<<pre1;for(long long i=1;i<=num1;i++)cout<<"AC";for(long long i=1;i<=n-num1*2-2;i++)cout<<"B";cout<<suf1;}}cout<<endl;if(m%2==0){if(num2==m/2){for(long long i=1;i<=num2;i++)cout<<"AC";}else{cout<<pre2;for(long long i=1;i<=num2;i++)cout<<"AC";for(long long i=1;i<=m-num2*2-2;i++)cout<<"B";cout<<suf2;}}else{if(num2==m/2){            if(m==1) cout<<pre2;else                if(pre2=='A'){                    for(long long i=1;i<=num2;i++)cout<<"AC";                    cout<<suf2;                }else if(suf2=='C'){                    cout<<pre2;                    for(long long i=1;i<=num2;i++)cout<<"AC";                }}else{cout<<pre2;for(long long i=1;i<=num2-1;i++)cout<<"AC";for(long long i=1;i<=m-num2*2-2;i++)cout<<"B";cout<<suf2;}}cout<<endl;return true;}int main(){#ifndef ONLINE_JUDGEfreopen("G:/in.txt","r",stdin);#endifcin>>k>>x>>n>>m;for(long long i=3;i<=k;i++){long long xx1tmp=xx1,xx2tmp=xx2;xx1+=x1;xx2+=x2;x1=xx1tmp,x2=xx2tmp;copy(tmp,num);add(num,lastnum);copy(lastnum,tmp);if(i==3)        num[1][2]=1;if(i>=4 && i%2==0)num[2][1]++;else if(i>=4)num[2][2]++;}for(long long num1=0;num1<=(n/2);num1++)for(long long num2=0;num2<=(m/2);num2++)for(long long suf1='A';suf1<='C';suf1++)for(long long suf2='A';suf2<='C';suf2++)for(long long pre1='A';pre1<='C';pre1++)for(long long pre2='A';pre2<='C';pre2++)if(can(num1,num2,suf1,suf2,pre1,pre2)){                                                                        ///cout<<xx1<<' '<<xx2<<endl;//                                                                        cout<<num1<<' '//                                                                        <<num2<<' '//                                                                        <<(char)pre1<<' '//                                                                        <<(char)pre2<<' '//                                                                        <<(char)suf1<<' '//                                                                        <<(char)suf2<<' '<<endl;if(print(num1,num2,suf1,suf2,pre1,pre2)){return 0;                                                                }}cout<<"Happy new year!"<<endl;}

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