7.20 Codeforces Beta Round #8
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A
原因：RE，fantasy 的字符串的长度可能大于原字符串。
B
题意：上下左右走，可能要避让障碍，问是否存在一个地图使得给定的路径为当前最短路径。
题型：构造，模拟
原因：map不熟，要判两个地方，一是不重复抵达，二是当前点除去前导点旁边的点不能事先经过。
解法：按照上面说的模拟一下就可以，这种方法相对来说效率高，但是代码写得多。可以直接遍历：一个点跟其后面步长大于1的点的距离不能小于1。
#include <iostream> #include <string.h> #include <algorithm> #include <stdio.h> #include <string> #include <map> #include <vector> #include <cmath> #include <set> #define ll long long #define PI 3.1415926535 #define AC ios::sync_with_stdio(0) using namespace std; const int inf=1e5+10; #define u dit[1]; bool cmp(const string& a,const string& b) { return a.length()<b.length(); } struct pt{ int x; int y; bool operator<(const pt&a)const{ //key为结构体时时要重载< if(x<a.x) return true; else if(x==a.x) return y<a.y; return false; } }; map<pt,int>mp; //int dit[4][2]={-1,0,0,1,1,0,0,-1}; string s; int main() { ios::sync_with_stdio(0); cin>>s; pt st; st.x=0; st.y=0; mp.insert(make_pair(st,1)); //忘记了 wa了 for(int i=0;i<s.length();i++) { if(s[i]==‘U‘) { st.x--; pt a={st.x-1,st.y},b={st.x,st.y+1},c={st.x,st.y-1}; if(mp.count(a)||mp.count(b)||mp.count(c)) { cout<<"BUG"<<endl; return 0; } } if(s[i]==‘D‘) { st.x++; pt a={st.x+1,st.y},b={st.x,st.y+1},c={st.x,st.y-1}; if(mp.count(a)||mp.count(b)||mp.count(c)) { cout<<"BUG"<<endl; return 0; } } if(s[i]==‘R‘) { st.y++; pt a={st.x+1,st.y},b={st.x-1,st.y},c={st.x,st.y+1}; if(mp.count(a)||mp.count(b)||mp.count(c)) { cout<<"BUG"<<endl; return 0; } } if(s[i]==‘L‘) { st.y--; pt a={st.x+1,st.y},b={st.x-1,st.y},c={st.x,st.y-1}; if(mp.count(a)||mp.count(b)||mp.count(c)) { cout<<"BUG"<<endl; return 0; } } if(mp.count(st)) { cout<<"BUG"<<endl; return 0; } mp.insert(make_pair(st,1)); //要用make_pair因为不会调用构造函数 } cout<<"OK"<<endl; }
/*下面是楼教主当年的代码*/ #include <vector> #include <list> #include <map> #include <set> #include <deque> #include <queue> #include <stack> #include <bitset> #include <algorithm> #include <functional> #include <numeric> #include <utility> #include <sstream> #include <iostream> #include <iomanip> #include <cstdio> #include <cmath> #include <cstdlib> #include <cctype> #include <string> #include <cstring> #include <cstdio> #include <cmath> #include <cstdlib> #include <ctime> using namespace std; //BEGINTEMPLATE_BY_ACRUSH_TOPCODER #define SIZE(X) ((int)(X.size()))//NOTES:SIZE( #define LENGTH(X) ((int)(X.length()))//NOTES:LENGTH( #define MP(X,Y) make_pair(X,Y)//NOTES:MP( typedef long long int64;//NOTES:int64 typedef unsigned long long uint64;//NOTES:uint64 #define two(X) (1<<(X))//NOTES:two( #define twoL(X) (((int64)(1))<<(X))//NOTES:twoL( #define contain(S,X) (((S)&two(X))!=0)//NOTES:contain( #define containL(S,X) (((S)&twoL(X))!=0)//NOTES:containL( const double pi=acos(-1.0);//NOTES:pi const double eps=1e-11;//NOTES:eps template<class T> inline void checkmin(T &a,T b){if(b<a) a=b;}//NOTES:checkmin( template<class T> inline void checkmax(T &a,T b){if(b>a) a=b;}//NOTES:checkmax( template<class T> inline T sqr(T x){return x*x;}//NOTES:sqr typedef pair<int,int> ipair;//NOTES:ipair template<class T> inline T lowbit(T n){return (n^(n-1))&n;}//NOTES:lowbit( template<class T> inline int countbit(T n){return (n==0)?0:(1+countbit(n&(n-1)));}//NOTES:countbit( //Numberic Functions template<class T> inline T gcd(T a,T b)//NOTES:gcd( {if(a<0)return gcd(-a,b);if(b<0)return gcd(a,-b);return (b==0)?a:gcd(b,a%b);} template<class T> inline T lcm(T a,T b)//NOTES:lcm( {if(a<0)return lcm(-a,b);if(b<0)return lcm(a,-b);return a*(b/gcd(a,b));} template<class T> inline T euclide(T a,T b,T &x,T &y)//NOTES:euclide( {if(a<0){T d=euclide(-a,b,x,y);x=-x;return d;} if(b<0){T d=euclide(a,-b,x,y);y=-y;return d;} if(b==0){x=1;y=0;return a;}else{T d=euclide(b,a%b,x,y);T t=x;x=y;y=t-(a/b)*y;return d;}} template<class T> inline vector<pair<T,int> > factorize(T n)//NOTES:factorize( {vector<pair<T,int> > R;for (T i=2;n>1;){if (n%i==0){int C=0;for (;n%i==0;C++,n/=i);R.push_back(make_pair(i,C));} i++;if (i>n/i) i=n;}if (n>1) R.push_back(make_pair(n,1));return R;} template<class T> inline bool isPrimeNumber(T n)//NOTES:isPrimeNumber( {if(n<=1)return false;for (T i=2;i*i<=n;i++) if (n%i==0) return false;return true;} template<class T> inline T eularFunction(T n)//NOTES:eularFunction( {vector<pair<T,int> > R=factorize(n);T r=n;for (int i=0;i<R.size();i++)r=r/R[i].first*(R[i].first-1);return r;} //Matrix Operations const int MaxMatrixSize=40;//NOTES:MaxMatrixSize template<class T> inline void showMatrix(int n,T A[MaxMatrixSize][MaxMatrixSize])//NOTES:showMatrix( {for (int i=0;i<n;i++){for (int j=0;j<n;j++)cout<<A[i][j];cout<<endl;}} template<class T> inline T checkMod(T n,T m) {return (n%m+m)%m;}//NOTES:checkMod( template<class T> inline void identityMatrix(int n,T A[MaxMatrixSize][MaxMatrixSize])//NOTES:identityMatrix( {for (int i=0;i<n;i++) for (int j=0;j<n;j++) A[i][j]=(i==j)?1:0;} template<class T> inline void addMatrix(int n,T C[MaxMatrixSize][MaxMatrixSize],T A[MaxMatrixSize][MaxMatrixSize],T B[MaxMatrixSize][MaxMatrixSize])//NOTES:addMatrix( {for (int i=0;i<n;i++) for (int j=0;j<n;j++) C[i][j]=A[i][j]+B[i][j];} template<class T> inline void subMatrix(int n,T C[MaxMatrixSize][MaxMatrixSize],T A[MaxMatrixSize][MaxMatrixSize],T B[MaxMatrixSize][MaxMatrixSize])//NOTES:subMatrix( {for (int i=0;i<n;i++) for (int j=0;j<n;j++) C[i][j]=A[i][j]-B[i][j];} template<class T> inline void mulMatrix(int n,T C[MaxMatrixSize][MaxMatrixSize],T _A[MaxMatrixSize][MaxMatrixSize],T _B[MaxMatrixSize][MaxMatrixSize])//NOTES:mulMatrix( { T A[MaxMatrixSize][MaxMatrixSize],B[MaxMatrixSize][MaxMatrixSize]; for (int i=0;i<n;i++) for (int j=0;j<n;j++) A[i][j]=_A[i][j],B[i][j]=_B[i][j],C[i][j]=0; for (int i=0;i<n;i++) for (int j=0;j<n;j++) for (int k=0;k<n;k++) C[i][j]+=A[i][k]*B[k][j];} template<class T> inline void addModMatrix(int n,T m,T C[MaxMatrixSize][MaxMatrixSize],T A[MaxMatrixSize][MaxMatrixSize],T B[MaxMatrixSize][MaxMatrixSize])//NOTES:addModMatrix( {for (int i=0;i<n;i++) for (int j=0;j<n;j++) C[i][j]=checkMod(A[i][j]+B[i][j],m);} template<class T> inline void subModMatrix(int n,T m,T C[MaxMatrixSize][MaxMatrixSize],T A[MaxMatrixSize][MaxMatrixSize],T B[MaxMatrixSize][MaxMatrixSize])//NOTES:subModMatrix( {for (int i=0;i<n;i++) for (int j=0;j<n;j++) C[i][j]=checkMod(A[i][j]-B[i][j],m);} template<class T> inline T multiplyMod(T a,T b,T m) {return (T)((((int64)(a)*(int64)(b)%(int64)(m))+(int64)(m))%(int64)(m));}//NOTES:multiplyMod( template<class T> inline void mulModMatrix(int n,T m,T C[MaxMatrixSize][MaxMatrixSize],T _A[MaxMatrixSize][MaxMatrixSize],T _B[MaxMatrixSize][MaxMatrixSize])//NOTES:mulModMatrix( { T A[MaxMatrixSize][MaxMatrixSize],B[MaxMatrixSize][MaxMatrixSize]; for (int i=0;i<n;i++) for (int j=0;j<n;j++) A[i][j]=_A[i][j],B[i][j]=_B[i][j],C[i][j]=0; for (int i=0;i<n;i++) for (int j=0;j<n;j++) for (int k=0;k<n;k++) C[i][j]=(C[i][j]+multiplyMod(A[i][k],B[k][j],m))%m;} template<class T> inline T powerMod(T p,int e,T m)//NOTES:powerMod( {if(e==0)return 1%m;else if(e%2==0){T t=powerMod(p,e/2,m);return multiplyMod(t,t,m);}else return multiplyMod(powerMod(p,e-1,m),p,m);} //Point&Line double dist(double x1,double y1,double x2,double y2){return sqrt(sqr(x1-x2)+sqr(y1-y2));}//NOTES:dist( double distR(double x1,double y1,double x2,double y2){return sqr(x1-x2)+sqr(y1-y2);}//NOTES:distR( template<class T> T cross(T x0,T y0,T x1,T y1,T x2,T y2){return (x1-x0)*(y2-y0)-(x2-x0)*(y1-y0);}//NOTES:cross( int crossOper(double x0,double y0,double x1,double y1,double x2,double y2)//NOTES:crossOper( {double t=(x1-x0)*(y2-y0)-(x2-x0)*(y1-y0);if (fabs(t)<=eps) return 0;return (t<0)?-1:1;} bool isIntersect(double x1,double y1,double x2,double y2,double x3,double y3,double x4,double y4)//NOTES:isIntersect( {return crossOper(x1,y1,x2,y2,x3,y3)*crossOper(x1,y1,x2,y2,x4,y4)<0 && crossOper(x3,y3,x4,y4,x1,y1)*crossOper(x3,y3,x4,y4,x2,y2)<0;} bool isMiddle(double s,double m,double t){return fabs(s-m)<=eps || fabs(t-m)<=eps || (s<m)!=(t<m);}//NOTES:isMiddle( //Translator bool isUpperCase(char c){return c>=‘A‘ && c<=‘Z‘;}//NOTES:isUpperCase( bool isLowerCase(char c){return c>=‘a‘ && c<=‘z‘;}//NOTES:isLowerCase( bool isLetter(char c){return c>=‘A‘ && c<=‘Z‘ || c>=‘a‘ && c<=‘z‘;}//NOTES:isLetter( bool isDigit(char c){return c>=‘0‘ && c<=‘9‘;}//NOTES:isDigit( char toLowerCase(char c){return (isUpperCase(c))?(c+32):c;}//NOTES:toLowerCase( char toUpperCase(char c){return (isLowerCase(c))?(c-32):c;}//NOTES:toUpperCase( template<class T> string toString(T n){ostringstream ost;ost<<n;ost.flush();return ost.str();}//NOTES:toString( int toInt(string s){int r=0;istringstream sin(s);sin>>r;return r;}//NOTES:toInt( int64 toInt64(string s){int64 r=0;istringstream sin(s);sin>>r;return r;}//NOTES:toInt64( double toDouble(string s){double r=0;istringstream sin(s);sin>>r;return r;}//NOTES:toDouble( template<class T> void stoa(string s,int &n,T A[]){n=0;istringstream sin(s);for(T v;sin>>v;A[n++]=v);}//NOTES:stoa( template<class T> void atos(int n,T A[],string &s){ostringstream sout;for(int i=0;i<n;i++){if(i>0)sout<<‘ ‘;sout<<A[i];}s=sout.str();}//NOTES:atos( template<class T> void atov(int n,T A[],vector<T> &vi){vi.clear();for (int i=0;i<n;i++) vi.push_back(A[i]);}//NOTES:atov( template<class T> void vtoa(vector<T> vi,int &n,T A[]){n=vi.size();for (int i=0;i<n;i++)A[i]=vi[i];}//NOTES:vtoa( template<class T> void stov(string s,vector<T> &vi){vi.clear();istringstream sin(s);for(T v;sin>>v;vi.push_bakc(v));}//NOTES:stov( template<class T> void vtos(vector<T> vi,string &s){ostringstream sout;for (int i=0;i<vi.size();i++){if(i>0)sout<<‘ ‘;sout<<vi[i];}s=sout.str();}//NOTES:vtos( //Fraction template<class T> struct Fraction{T a,b;Fraction(T a=0,T b=1);string toString();};//NOTES:Fraction template<class T> Fraction<T>::Fraction(T a,T b){T d=gcd(a,b);a/=d;b/=d;if (b<0) a=-a,b=-b;this->a=a;this->b=b;} template<class T> string Fraction<T>::toString(){ostringstream sout;sout<<a<<"/"<<b;return sout.str();} template<class T> Fraction<T> operator+(Fraction<T> p,Fraction<T> q){return Fraction<T>(p.a*q.b+q.a*p.b,p.b*q.b);} template<class T> Fraction<T> operator-(Fraction<T> p,Fraction<T> q){return Fraction<T>(p.a*q.b-q.a*p.b,p.b*q.b);} template<class T> Fraction<T> operator*(Fraction<T> p,Fraction<T> q){return Fraction<T>(p.a*q.a,p.b*q.b);} template<class T> Fraction<T> operator/(Fraction<T> p,Fraction<T> q){return Fraction<T>(p.a*q.b,p.b*q.a);} //ENDTEMPLATE_BY_ACRUSH_TOPCODER int main() { #ifdef _MSC_VER freopen("input.txt","r",stdin); #endif int x[105],y[105]; x[0]=y[0]=0; int n=1; char s[105]; scanf("%s",s); for (int i=0;s[i];i++) { x[n]=x[n-1]; y[n]=y[n-1]; if (s[i]==‘L‘) x[n]--; if (s[i]==‘R‘) x[n]++; if (s[i]==‘U‘) y[n]--; if (s[i]==‘D‘) y[n]++; n++; } bool isGood=true; for (int i=0;i<n;i++) for (int j=i+2;j<n;j++) if (abs(x[i]-x[j])+abs(y[i]-y[j])<=1) isGood=false; if (isGood) printf("OK "); else printf("BUG "); return 0; }
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