JAG 模擬地区予選 2011 I問題
解法
多項式の比較 + Dinic法
実装(C++)
遅いフローアルゴリズムで提出してしまい1TLE
#include <algorithm> #include <vector> #include <iostream> #include <set> #include <map> #include <stack> #include <queue> #include <deque> #include <iomanip> #include <functional> #include <cstdlib> #include <cstdio> #include <cmath> #include <cstring> #include <iterator> #include <sstream> using namespace std; #define REP(i,x) for(int i=0;i<(int)x;i++) #define FOR(it,x) for(__typeof(x.begin()) it=x.begin();it!=x.end();it++) typedef map<int,int> P; const int MAX_V=100; struct edge{int to;P cap;int rev;}; vector<edge> G[MAX_V]; bool used[MAX_V]; vector<string> split(string exp,string delimiter){ int L=delimiter.size(),l=exp.size(); vector<string> res;string tmp=""; REP(i,l){ if(i<=l-L&&exp.substr(i,L)==delimiter){ res.push_back(tmp); tmp=""; i+=L-1; }else{ tmp+=exp[i]; } } if(tmp!="")res.push_back(tmp); return res; } istream &operator>>(istream &is,P &a){ a.clear(); string s; is>>s; vector<string> plused=split(s,"+"); REP(i,plused.size()){ string tmp=plused[i]; vector<string> strs=split(tmp,"x"); if(strs[0].size()==0)strs[0]="1"; if(strs.size()==1&&tmp.find("x")==string::npos){ a[0]+=atoi(strs[0].c_str()); }else{ if(strs.size()==1){ a[1]+=atoi(strs[0].c_str()); }else{ a[atoi(strs[1].substr(1).c_str())]+=atoi(strs[0].c_str()); } } } return is; } ostream &operator<<(ostream &os,P tmp){ bool init=0; FOR(it,tmp){ if(it->second==0){ tmp.erase(it--); } } if(tmp.size()==0){ cout<<"0"; }else{ for(P::reverse_iterator it=tmp.rbegin();it!=tmp.rend();it++){ if(init){ if(it->second>0){ cout<<"+"; } } if(it->second==0)continue; if(it->second==-1) cout<<"-"; else if(it->second==1){ }else{ cout<<it->second; } if(it->first==1){ cout<<"x"; }else if(it->first==0){ if(abs(it->second)==1){ cout<<1; } }else{ cout<<"x^"<<it->first; } init++; } } return os; } P operator+(const P &a,const P &b){ P res(b); FOR(it,a){ res[it->first]+=it->second; } return res; } P operator-(const P &a,const P &b){ P res(a); FOR(it,b){ res[it->first]-=it->second; } return res; } bool operator<(const P &a,const P &b){ P tmp=a-b; for(P::reverse_iterator it=tmp.rbegin();it!=tmp.rend();it++){ //cout<<"!"<<it->first<<","<<it->second<<endl; if(it->second>0)return false; if(it->second<0)return true; } return false; } bool operator>(const P &a,const P &b){ return b<a; //a>b; } int level[MAX_V]; int iter[MAX_V]; void add_edge(int from,int to,P cap){ G[from].push_back((edge){to,cap,G[to].size()}); G[to].push_back((edge){from,P(),G[from].size()-1}); } P dfs(int v,int t,P f){ //cout<<v<<","<<f<<endl; if(v==t)return f; for(int &i=iter[v];i<(int)G[v].size();i++){ edge &e=G[v][i]; if(e.cap>P()&&level[v]<level[e.to]){ P next=f; if(f>e.cap)next=e.cap; P d=dfs(e.to,t,next); if(d>P()){ e.cap=e.cap-d; G[e.to][e.rev].cap=G[e.to][e.rev].cap+d; return d; } } } return P(); } void bfs(int s){ memset(level,-1,sizeof(level)); queue<int> que; level[s]=0; que.push(s); while(!que.empty()){ int v=que.front();que.pop(); for(int i=0;i<(int)G[v].size();i++){ edge &e=G[v][i]; if(e.cap>P()&&level[e.to]<0){ level[e.to]=level[v]+1; que.push(e.to); } } } } P max_flow(int s,int t){ P flow; while(1){ bfs(s); if(level[t]<0)return flow; memset(iter,0,sizeof(iter)); P INF; INF[100]=99999999; P f; while((f=dfs(s,t,INF))>P()) flow=flow+f; } } int main() { int N,M; while(cin>>N>>M){ if(N==0)break; for(int i=0;i<N;i++){ G[i].clear(); } for(int i=0;i<M;i++){ int s,t;P c; cin>>s>>t>>c; s--;t--; add_edge(s,t,c); add_edge(t,s,c); } cout<<max_flow(0,N-1)<<endl; } return 0; }