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 14 int main(){ 15 #ifndef ONLINE_JUDGE 16 // freopen("input.txt","r",stdin); 17 #endif 18 std::ios::sync_with_stdio(false); 19 string str; 20 cin>>str; 21 int big=0,small=0; 22 for(int i=0;i<str.length();i++){ 23 if(str[i]>='A'&&str[i]<='Z'){ 24 big++; 25 } 26 else{ 27 small++; 28 } 29 } 30 if(big<=small){ 31 for(int i=0;i<str.length();i++){ 32 if(str[i]>='A'&&str[i]<='Z'){ 33 str[i]+=32; 34 } 35 cout<<str[i]; 36 } 37 } 38 else{ 39 for(int i=0;i<str.length();i++){ 40 if(str[i]>='a'&&str[i]<='z'){ 41 str[i]-=32; 42 } 43 cout<<str[i]; 44 } 45 } 46 }
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[105]; 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=0; 23 int sum=0; 24 int ji=0x3f3f3f3f,ou=0x3f3f3f3f; 25 for(int i=1;i<=n;i++){ 26 cin>>a[i]; 27 if(a[i]%2&&a[i]<ji) ji=a[i]; 28 if((a[i]%2==0)&&a[i]<ou) ou=a[i]; 29 sum+=a[i]; 30 } 31 if(sum%2)cout<<sum<<endl; 32 else{ 33 if(ji!=0x3f3f3f3f) cout<<sum-ji<<endl; 34 else cout<<0<<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 14 int main(){ 15 #ifndef ONLINE_JUDGE 16 freopen("input.txt","r",stdin); 17 #endif 18 std::ios::sync_with_stdio(false); 19 int n; 20 map<char,int>mp; 21 string str; 22 cin>>n>>str; 23 int prex=0,prey=0; 24 int num=0; 25 rep(i,0,str.length()){ 26 if(str[i]!='?') 27 mp[str[i]]=1; 28 } 29 int len=str.length()+1; 30 int L=len-1; 31 len/=2; 32 rep(i,0,len){ 33 if(str[i]=='?'&&str[L-i-1]=='?') num++; 34 } 35 int k=n-mp.size(); 36 rep(i,0,len){ 37 if(num<k){ 38 cout<<"IMPOSSIBLE"<<endl; 39 return 0; 40 } 41 if(i==L-i-1){ 42 if(str[i]=='?'){ 43 if(num-1>=k){ 44 if(mp['a']){ 45 str[i]='a'; 46 num--; 47 } 48 else{ 49 str[i]='a'; 50 mp['a']=1; 51 num--; 52 k--; 53 } 54 } 55 else if(num-1>=k-1){ 56 int flag=1; 57 rep(j,0,26){ 58 if(mp[char(j+'a')]==0){ 59 mp[char(j+'a')]=1; 60 num--; 61 k--; 62 str[i]=char(j+'a'); 63 flag=0; 64 break; 65 } 66 } 67 if(flag){ 68 cout<<"IMPOSSIBLE"<<endl; 69 return 0; 70 } 71 } 72 else{ 73 cout<<"IMPOSSIBLE"<<endl; 74 return 0; 75 } 76 } 77 } 78 else if(str[i]=='?'&&str[L-i-1]!='?'){ 79 str[i]=str[L-i-1]; 80 } 81 else if(str[i]!='?'&&str[L-i-1]=='?'){ 82 str[L-i-1]=str[i]; 83 } 84 else if(str[i]=='?'&&str[L-i-1]=='?'){ 85 prex=i,prey=L-i-1; 86 if(num-1>=k){ 87 if(mp['a']){ 88 str[i]='a'; 89 str[L-i-1]='a'; 90 num-=1; 91 } 92 else{ 93 mp['a']=1; 94 k--; 95 num-=1; 96 str[i]='a'; 97 str[L-i-1]='a'; 98 } 99 } 100 else if(num-1>=k-1){ 101 int flag=1; 102 rep(j,0,26){ 103 if(mp[char(j+'a')]==0){ 104 mp[char(j+'a')]=1; 105 k--; 106 num-=1; 107 str[i]=char(j+'a'); 108 str[L-i-1]=char(j+'a'); 109 flag=0; 110 break; 111 } 112 } 113 if(flag){ 114 cout<<"IMPOSSIBLE"<<endl; 115 return 0; 116 } 117 } 118 else{ 119 cout<<"IMPOSSIBLE"<<endl; 120 return 0; 121 } 122 } 123 else if(str[i]!='?'&&str[L-i-1]!='?'){ 124 if(str[i]!=str[L-i-1]){ 125 cout<<"IMPOSSIBLE"<<endl; 126 return 0; 127 } 128 } 129 } 130 // cout<<k<<endl; 131 // cout<<prex<<" "<<prey<<endl; 132 if(k==1){ 133 int flag=1; 134 rep(i,0,26){ 135 if(mp[char(i+'a')]==0){ 136 str[prex]=char(i+'a'); 137 str[prey]=char(i+'a'); 138 flag=0; 139 break; 140 k--; 141 } 142 } 143 if(flag){ 144 cout<<"IMPOSSIBLE"<<endl; 145 return 0; 146 } 147 } 148 cout<<str<<endl; 149 }
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[300005],b[300005]; 14 int book[300005]; 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,0,3*n) cin>>b[i]; 24 rep(i,0,3*n) cin>>a[i]; 25 int k; 26 cin>>k; 27 int pos=0,group,pp=0; 28 while(a[pos]!=k) pos++; 29 group=pos/3+1; 30 rep(i,0,3*(group-1)) book[a[i]]=true; 31 rep(i,0,3*n) if(!book[b[i]]){ 32 pp=i;break; 33 } 34 if(a[pos]!=b[pp]) sort(a,a+3*n); 35 else{ 36 int flag=-1; 37 rep(i,3*(group-1),3*group) if(i!=pos) flag=max(flag,a[i]); 38 sort(a,a+3*group); 39 int pos=0; 40 while(a[pos]!=flag) pos++; 41 sort(a+pos+1,a+3*n); 42 } 43 rep(i,0,3*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[3005]; 14 int book[3005][3005]; 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[9000005]; 22 23 int bfs(){ 24 sair s,e; 25 s.pre=0,s.now=1,s.step=0; 26 int L=1,R=1; 27 Q[R++]=s; 28 int u; 29 while(L<R){ 30 s=Q[L++]; 31 rep(i,0,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+1; 39 book[e.pre][e.now]=L-1; 40 Q[R++]=e; 41 42 if(u==n){ 43 cout<<e.step<<endl; 44 return R-1; 45 } 46 47 } 48 } 49 } 50 } 51 return 0; 52 } 53 54 void dfs(int pos){ 55 if(pos==0) exit(0); 56 if(pos==1){ 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,0,m){ 72 cin>>u>>v; 73 ve[u].pb(v); 74 ve[v].pb(u); 75 } 76 int w; 77 rep(i,0,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<<-1<<endl; 83 else{ 84 dfs(pos); 85 } 86 }