Codeforces Beta Round #55 (Div. 2)

Codeforces Beta Round #55 (Div. 2)

http://codeforces.com/contest/59

A

 #include<bits/stdc++.h>
 using namespace std;
 #define lson l,mid,rt<<1
 #define rson mid+1,r,rt<<1|1
 #define sqr(x) ((x)*(x))
 #define pb push_back
 #define eb emplace_back
 #define maxn 1000005
 #define rep(k,i,j) for(int k=i;k<j;k++)
 typedef long long ll;
 typedef unsigned long long ull;

 int main(){
     #ifndef ONLINE_JUDGE
        // freopen("input.txt","r",stdin);
     #endif
     std::ios::sync_with_stdio(false);
     string str;
     cin>>str;
     int big=,small=;
     for(int i=;i<str.length();i++){
         if(str[i]>='A'&&str[i]<='Z'){
             big++;
         }
         else{
             small++;
         }
     }
     if(big<=small){
         for(int i=;i<str.length();i++){
             if(str[i]>='A'&&str[i]<='Z'){
                 str[i]+=;
             }
             cout<<str[i];
         }
     }
     else{
        for(int i=;i<str.length();i++){
             if(str[i]>='a'&&str[i]<='z'){
                 str[i]-=;
             }
             cout<<str[i];
         }
     }
 }

B

 #include<bits/stdc++.h>
 using namespace std;
 #define lson l,mid,rt<<1
 #define rson mid+1,r,rt<<1|1
 #define sqr(x) ((x)*(x))
 #define pb push_back
 #define eb emplace_back
 #define maxn 1000005
 #define rep(k,i,j) for(int k=i;k<j;k++)
 typedef long long ll;
 typedef unsigned long long ull;

 int a[];

 int main(){
     #ifndef ONLINE_JUDGE
        // freopen("input.txt","r",stdin);
     #endif
     std::ios::sync_with_stdio(false);
     int n;
     cin>>n;
     int ans=;
     int sum=;
     int ji=0x3f3f3f3f,ou=0x3f3f3f3f;
     for(int i=;i<=n;i++){
         cin>>a[i];
         if(a[i]%&&a[i]<ji) ji=a[i];
         if((a[i]%==)&&a[i]<ou) ou=a[i];
         sum+=a[i];
     }
     if(sum%)cout<<sum<<endl;
     else{
         if(ji!=0x3f3f3f3f) cout<<sum-ji<<endl;
         else cout<<<<endl;
     }
 }

C

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

 #include<bits/stdc++.h>
 using namespace std;
 #define lson l,mid,rt<<1
 #define rson mid+1,r,rt<<1|1
 #define sqr(x) ((x)*(x))
 #define pb push_back
 #define eb emplace_back
 #define maxn 1000005
 #define rep(k,i,j) for(int k=i;k<j;k++)
 typedef long long ll;
 typedef unsigned long long ull;

 int main(){
     #ifndef ONLINE_JUDGE
         freopen("input.txt","r",stdin);
     #endif
     std::ios::sync_with_stdio(false);
     int n;
     map<char,int>mp;
     string str;
     cin>>n>>str;
     int prex=,prey=;
     int num=;
     rep(i,,str.length()){
         if(str[i]!='?')
             mp[str[i]]=;
     }
     int len=str.length()+;
     int L=len-;
     len/=;
     rep(i,,len){
         if(str[i]=='?'&&str[L-i-]=='?') num++;
     }
     int k=n-mp.size();
     rep(i,,len){
         if(num<k){
             cout<<"IMPOSSIBLE"<<endl;
             return ;
         }
         if(i==L-i-){
             if(str[i]=='?'){
                 if(num->=k){
                     if(mp['a']){
                         str[i]='a';
                         num--;
                     }
                     else{
                         str[i]='a';
                         mp['a']=;
                         num--;
                         k--;
                     }
                 }
                 else if(num->=k-){
                     int flag=;
                     rep(j,,){
                         if(mp[char(j+'a')]==){
                             mp[char(j+'a')]=;
                             num--;
                             k--;
                             str[i]=char(j+'a');
                             flag=;
                             break;
                         }
                     }
                     if(flag){
                         cout<<"IMPOSSIBLE"<<endl;
                         return ;
                     }
                 }
                 else{
                     cout<<"IMPOSSIBLE"<<endl;
                     return ;
                 }
             }
         }
         else if(str[i]=='?'&&str[L-i-]!='?'){
             str[i]=str[L-i-];
         }
         else if(str[i]!='?'&&str[L-i-]=='?'){
             str[L-i-]=str[i];
         }
         else if(str[i]=='?'&&str[L-i-]=='?'){
             prex=i,prey=L-i-;
             if(num->=k){
                 if(mp['a']){
                     str[i]='a';
                     str[L-i-]='a';
                     num-=;
                 }
                 else{
                     mp['a']=;
                     k--;
                     num-=;
                     str[i]='a';
                     str[L-i-]='a';
                 }
             }
             else if(num->=k-){
                 int flag=;
                 rep(j,,){
                     if(mp[char(j+'a')]==){
                         mp[char(j+'a')]=;
                         k--;
                         num-=;
                         str[i]=char(j+'a');
                         str[L-i-]=char(j+'a');
                         flag=;
                         break;
                     }
                 }
                 if(flag){
                     cout<<"IMPOSSIBLE"<<endl;
                     return ;
                 }
             }
             else{
                 cout<<"IMPOSSIBLE"<<endl;
                 return ;
             }
         }
         else if(str[i]!='?'&&str[L-i-]!='?'){
             if(str[i]!=str[L-i-]){
                 cout<<"IMPOSSIBLE"<<endl;
                 return ;
             }
         }
     }
    // cout<<k<<endl;
    // cout<<prex<<" "<<prey<<endl;
     if(k==){
         int flag=;
         rep(i,,){
             if(mp[char(i+'a')]==){
                 str[prex]=char(i+'a');
                 str[prey]=char(i+'a');
                 flag=;
                 break;
                 k--;
             }
         }
         if(flag){
             cout<<"IMPOSSIBLE"<<endl;
             return ;
         }
     }
     cout<<str<<endl;
 }

D

模拟

 #include<bits/stdc++.h>
 using namespace std;
 #define lson l,mid,rt<<1
 #define rson mid+1,r,rt<<1|1
 #define sqr(x) ((x)*(x))
 #define pb push_back
 #define eb emplace_back
 #define maxn 1000005
 #define rep(k,i,j) for(int k=i;k<j;k++)
 typedef long long ll;
 typedef unsigned long long ull;

 int a[],b[];
 int book[];

 int main(){
     #ifndef ONLINE_JUDGE
         freopen("input.txt","r",stdin);
     #endif
     std::ios::sync_with_stdio(false);
     int n;
     cin>>n;
     rep(i,,*n) cin>>b[i];
     rep(i,,*n) cin>>a[i];
     int k;
     cin>>k;
     int pos=,group,pp=;
     while(a[pos]!=k) pos++;
     group=pos/+;
     rep(i,,*(group-)) book[a[i]]=true;
     rep(i,,*n) if(!book[b[i]]){
         pp=i;break;
     }
     if(a[pos]!=b[pp]) sort(a,a+*n);
     else{
         int flag=-;
         rep(i,*(group-),*group) if(i!=pos) flag=max(flag,a[i]);
         sort(a,a+*group);
         int pos=;
         while(a[pos]!=flag) pos++;
         sort(a+pos+,a+*n);
     }
     rep(i,,*n) if(a[i]!=k) cout<<a[i]<<" ";
 }

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

 #include<bits/stdc++.h>
 using namespace std;
 #define lson l,mid,rt<<1
 #define rson mid+1,r,rt<<1|1
 #define sqr(x) ((x)*(x))
 #define pb push_back
 #define eb emplace_back
 #define maxn 1000005
 #define rep(k,i,j) for(int k=i;k<j;k++)
 typedef long long ll;
 typedef unsigned long long ull;

 vector<int>ve[];
 int book[][];
 int n,m,k;
 set< pair<int,pair<int,int> > >se;
 set< pair<int,pair<int,int> > >::iterator it;

 struct sair{
     int pre,now,step;
 }Q[];

 int bfs(){
     sair s,e;
     s.pre=,s.now=,s.step=;
     int L=,R=;
     Q[R++]=s;
     int u;
     while(L<R){
         s=Q[L++];
         rep(i,,ve[s.now].size()){
             u=ve[s.now][i];
             if(!book[s.now][u]){
                 it=se.find(make_pair(s.pre,make_pair(s.now,u)));
                 if(it==se.end()){
                     e.pre=s.now;
                     e.now=u;
                     e.step=s.step+;
                     book[e.pre][e.now]=L-;
                     Q[R++]=e;

                     if(u==n){
                         cout<<e.step<<endl;
                         return R-;
                     }

                 }
             }
         }
     }
     return ;
 }

 void dfs(int pos){
     if(pos==) exit();
     if(pos==){
         cout<<Q[pos].now<<" ";
         return;
     }
     dfs(book[Q[pos].pre][Q[pos].now]);
     cout<<Q[pos].now<<" ";
 }

 int main(){
     #ifndef ONLINE_JUDGE
         freopen("input.txt","r",stdin);
     #endif
     std::ios::sync_with_stdio(false);
     cin>>n>>m>>k;
     int u,v;
     rep(i,,m){
         cin>>u>>v;
         ve[u].pb(v);
         ve[v].pb(u);
     }
     int w;
     rep(i,,k){
         cin>>u>>v>>w;
         se.insert(make_pair(u,make_pair(v,w)));
     }
     int pos=bfs();
     if(!pos) cout<<-<<endl;
     else{
         dfs(pos);
     }
 }