Codeforces Beta Round #55 (Div. 2)

http://codeforces.com/contest/59

A

  1.  #include<bits/stdc++.h>
  2.  using namespace std;
  3.  #define lson l,mid,rt<<1
  4.  #define rson mid+1,r,rt<<1|1
  5.  #define sqr(x) ((x)*(x))
  6.  #define pb push_back
  7.  #define eb emplace_back
  8.  #define maxn 1000005
  9.  #define rep(k,i,j) for(int k=i;k<j;k++)
  10.  typedef long long ll;
  11.  typedef unsigned long long ull;
  12.  
  13.  int main(){
  14.      #ifndef ONLINE_JUDGE
  15.         // freopen("input.txt","r",stdin);
  16.      #endif
  17.      std::ios::sync_with_stdio(false);
  18.      string str;
  19.      cin>>str;
  20.      int big=,small=;
  21.      for(int i=;i<str.length();i++){
  22.          if(str[i]>='A'&&str[i]<='Z'){
  23.              big++;
  24.          }
  25.          else{
  26.              small++;
  27.          }
  28.      }
  29.      if(big<=small){
  30.          for(int i=;i<str.length();i++){
  31.              if(str[i]>='A'&&str[i]<='Z'){
  32.                  str[i]+=;
  33.              }
  34.              cout<<str[i];
  35.          }
  36.      }
  37.      else{
  38.         for(int i=;i<str.length();i++){
  39.              if(str[i]>='a'&&str[i]<='z'){
  40.                  str[i]-=;
  41.              }
  42.              cout<<str[i];
  43.          }
  44.      }
  45.  }

B

  1.  #include<bits/stdc++.h>
  2.  using namespace std;
  3.  #define lson l,mid,rt<<1
  4.  #define rson mid+1,r,rt<<1|1
  5.  #define sqr(x) ((x)*(x))
  6.  #define pb push_back
  7.  #define eb emplace_back
  8.  #define maxn 1000005
  9.  #define rep(k,i,j) for(int k=i;k<j;k++)
  10.  typedef long long ll;
  11.  typedef unsigned long long ull;
  12.  
  13.  int a[];
  14.  
  15.  int main(){
  16.      #ifndef ONLINE_JUDGE
  17.         // freopen("input.txt","r",stdin);
  18.      #endif
  19.      std::ios::sync_with_stdio(false);
  20.      int n;
  21.      cin>>n;
  22.      int ans=;
  23.      int sum=;
  24.      int ji=0x3f3f3f3f,ou=0x3f3f3f3f;
  25.      for(int i=;i<=n;i++){
  26.          cin>>a[i];
  27.          if(a[i]%&&a[i]<ji) ji=a[i];
  28.          if((a[i]%==)&&a[i]<ou) ou=a[i];
  29.          sum+=a[i];
  30.      }
  31.      if(sum%)cout<<sum<<endl;
  32.      else{
  33.          if(ji!=0x3f3f3f3f) cout<<sum-ji<<endl;
  34.          else cout<<<<endl;
  35.      }
  36.  }

C

模拟，找出前str.length()/2中，str[i]=='?'&&str[str.length()-1-i]=='?'的个数，然后贪心

  1.  #include<bits/stdc++.h>
  2.  using namespace std;
  3.  #define lson l,mid,rt<<1
  4.  #define rson mid+1,r,rt<<1|1
  5.  #define sqr(x) ((x)*(x))
  6.  #define pb push_back
  7.  #define eb emplace_back
  8.  #define maxn 1000005
  9.  #define rep(k,i,j) for(int k=i;k<j;k++)
  10.  typedef long long ll;
  11.  typedef unsigned long long ull;
  12.  
  13.  int main(){
  14.      #ifndef ONLINE_JUDGE
  15.          freopen("input.txt","r",stdin);
  16.      #endif
  17.      std::ios::sync_with_stdio(false);
  18.      int n;
  19.      map<char,int>mp;
  20.      string str;
  21.      cin>>n>>str;
  22.      int prex=,prey=;
  23.      int num=;
  24.      rep(i,,str.length()){
  25.          if(str[i]!='?')
  26.              mp[str[i]]=;
  27.      }
  28.      int len=str.length()+;
  29.      int L=len-;
  30.      len/=;
  31.      rep(i,,len){
  32.          if(str[i]=='?'&&str[L-i-]=='?') num++;
  33.      }
  34.      int k=n-mp.size();
  35.      rep(i,,len){
  36.          if(num<k){
  37.              cout<<"IMPOSSIBLE"<<endl;
  38.              return ;
  39.          }
  40.          if(i==L-i-){
  41.              if(str[i]=='?'){
  42.                  if(num->=k){
  43.                      if(mp['a']){
  44.                          str[i]='a';
  45.                          num--;
  46.                      }
  47.                      else{
  48.                          str[i]='a';
  49.                          mp['a']=;
  50.                          num--;
  51.                          k--;
  52.                      }
  53.                  }
  54.                  else if(num->=k-){
  55.                      int flag=;
  56.                      rep(j,,){
  57.                          if(mp[char(j+'a')]==){
  58.                              mp[char(j+'a')]=;
  59.                              num--;
  60.                              k--;
  61.                              str[i]=char(j+'a');
  62.                              flag=;
  63.                              break;
  64.                          }
  65.                      }
  66.                      if(flag){
  67.                          cout<<"IMPOSSIBLE"<<endl;
  68.                          return ;
  69.                      }
  70.                  }
  71.                  else{
  72.                      cout<<"IMPOSSIBLE"<<endl;
  73.                      return ;
  74.                  }
  75.              }
  76.          }
  77.          else if(str[i]=='?'&&str[L-i-]!='?'){
  78.              str[i]=str[L-i-];
  79.          }
  80.          else if(str[i]!='?'&&str[L-i-]=='?'){
  81.              str[L-i-]=str[i];
  82.          }
  83.          else if(str[i]=='?'&&str[L-i-]=='?'){
  84.              prex=i,prey=L-i-;
  85.              if(num->=k){
  86.                  if(mp['a']){
  87.                      str[i]='a';
  88.                      str[L-i-]='a';
  89.                      num-=;
  90.                  }
  91.                  else{
  92.                      mp['a']=;
  93.                      k--;
  94.                      num-=;
  95.                      str[i]='a';
  96.                      str[L-i-]='a';
  97.                  }
  98.              }
  99.              else if(num->=k-){
  100.                  int flag=;
  101.                  rep(j,,){
  102.                      if(mp[char(j+'a')]==){
  103.                          mp[char(j+'a')]=;
  104.                          k--;
  105.                          num-=;
  106.                          str[i]=char(j+'a');
  107.                          str[L-i-]=char(j+'a');
  108.                          flag=;
  109.                          break;
  110.                      }
  111.                  }
  112.                  if(flag){
  113.                      cout<<"IMPOSSIBLE"<<endl;
  114.                      return ;
  115.                  }
  116.              }
  117.              else{
  118.                  cout<<"IMPOSSIBLE"<<endl;
  119.                  return ;
  120.              }
  121.          }
  122.          else if(str[i]!='?'&&str[L-i-]!='?'){
  123.              if(str[i]!=str[L-i-]){
  124.                  cout<<"IMPOSSIBLE"<<endl;
  125.                  return ;
  126.              }
  127.          }
  128.      }
  129.     // cout<<k<<endl;
  130.     // cout<<prex<<" "<<prey<<endl;
  131.      if(k==){
  132.          int flag=;
  133.          rep(i,,){
  134.              if(mp[char(i+'a')]==){
  135.                  str[prex]=char(i+'a');
  136.                  str[prey]=char(i+'a');
  137.                  flag=;
  138.                  break;
  139.                  k--;
  140.              }
  141.          }
  142.          if(flag){
  143.              cout<<"IMPOSSIBLE"<<endl;
  144.              return ;
  145.          }
  146.      }
  147.      cout<<str<<endl;
  148.  }

D

模拟

  1.  #include<bits/stdc++.h>
  2.  using namespace std;
  3.  #define lson l,mid,rt<<1
  4.  #define rson mid+1,r,rt<<1|1
  5.  #define sqr(x) ((x)*(x))
  6.  #define pb push_back
  7.  #define eb emplace_back
  8.  #define maxn 1000005
  9.  #define rep(k,i,j) for(int k=i;k<j;k++)
  10.  typedef long long ll;
  11.  typedef unsigned long long ull;
  12.  
  13.  int a[],b[];
  14.  int book[];
  15.  
  16.  int main(){
  17.      #ifndef ONLINE_JUDGE
  18.          freopen("input.txt","r",stdin);
  19.      #endif
  20.      std::ios::sync_with_stdio(false);
  21.      int n;
  22.      cin>>n;
  23.      rep(i,,*n) cin>>b[i];
  24.      rep(i,,*n) cin>>a[i];
  25.      int k;
  26.      cin>>k;
  27.      int pos=,group,pp=;
  28.      while(a[pos]!=k) pos++;
  29.      group=pos/+;
  30.      rep(i,,*(group-)) book[a[i]]=true;
  31.      rep(i,,*n) if(!book[b[i]]){
  32.          pp=i;break;
  33.      }
  34.      if(a[pos]!=b[pp]) sort(a,a+*n);
  35.      else{
  36.          int flag=-;
  37.          rep(i,*(group-),*group) if(i!=pos) flag=max(flag,a[i]);
  38.          sort(a,a+*group);
  39.          int pos=;
  40.          while(a[pos]!=flag) pos++;
  41.          sort(a+pos+,a+*n);
  42.      }
  43.      rep(i,,*n) if(a[i]!=k) cout<<a[i]<<" ";
  44.  }

E

用bfs找最短路，book[i][j]表示当前走到j,它的前一步是在i位置，然后book[i][j]记录的是它的前一步在队列中的位置

  1.  #include<bits/stdc++.h>
  2.  using namespace std;
  3.  #define lson l,mid,rt<<1
  4.  #define rson mid+1,r,rt<<1|1
  5.  #define sqr(x) ((x)*(x))
  6.  #define pb push_back
  7.  #define eb emplace_back
  8.  #define maxn 1000005
  9.  #define rep(k,i,j) for(int k=i;k<j;k++)
  10.  typedef long long ll;
  11.  typedef unsigned long long ull;
  12.  
  13.  vector<int>ve[];
  14.  int book[][];
  15.  int n,m,k;
  16.  set< pair<int,pair<int,int> > >se;
  17.  set< pair<int,pair<int,int> > >::iterator it;
  18.  
  19.  struct sair{
  20.      int pre,now,step;
  21.  }Q[];
  22.  
  23.  int bfs(){
  24.      sair s,e;
  25.      s.pre=,s.now=,s.step=;
  26.      int L=,R=;
  27.      Q[R++]=s;
  28.      int u;
  29.      while(L<R){
  30.          s=Q[L++];
  31.          rep(i,,ve[s.now].size()){
  32.              u=ve[s.now][i];
  33.              if(!book[s.now][u]){
  34.                  it=se.find(make_pair(s.pre,make_pair(s.now,u)));
  35.                  if(it==se.end()){
  36.                      e.pre=s.now;
  37.                      e.now=u;
  38.                      e.step=s.step+;
  39.                      book[e.pre][e.now]=L-;
  40.                      Q[R++]=e;
  41.  
  42.                      if(u==n){
  43.                          cout<<e.step<<endl;
  44.                          return R-;
  45.                      }
  46.  
  47.                  }
  48.              }
  49.          }
  50.      }
  51.      return ;
  52.  }
  53.  
  54.  void dfs(int pos){
  55.      if(pos==) exit();
  56.      if(pos==){
  57.          cout<<Q[pos].now<<" ";
  58.          return;
  59.      }
  60.      dfs(book[Q[pos].pre][Q[pos].now]);
  61.      cout<<Q[pos].now<<" ";
  62.  }
  63.  
  64.  int main(){
  65.      #ifndef ONLINE_JUDGE
  66.          freopen("input.txt","r",stdin);
  67.      #endif
  68.      std::ios::sync_with_stdio(false);
  69.      cin>>n>>m>>k;
  70.      int u,v;
  71.      rep(i,,m){
  72.          cin>>u>>v;
  73.          ve[u].pb(v);
  74.          ve[v].pb(u);
  75.      }
  76.      int w;
  77.      rep(i,,k){
  78.          cin>>u>>v>>w;
  79.          se.insert(make_pair(u,make_pair(v,w)));
  80.      }
  81.      int pos=bfs();
  82.      if(!pos) cout<<-<<endl;
  83.      else{
  84.          dfs(pos);
  85.      }
  86.  }

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