Codeforces Beta Round #31 (Div. 2, Codeforces format)

Codeforces Beta Round #31 (Div. 2, Codeforces format)

http://codeforces.com/contest/31

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 maxn 1000005
 typedef long long ll;
 typedef unsigned long long ull;
 /*#ifndef ONLINE_JUDGE
         freopen("1.txt","r",stdin);
 #endif */

 int a[];

 int main(){
     #ifndef ONLINE_JUDGE
         freopen("1.txt","r",stdin);
     #endif
     std::ios::sync_with_stdio(false);
     int n;
     cin>>n;
     for(int i=;i<=n;i++) cin>>a[i];
     for(int i=;i<=n;i++){
         for(int j=;j<=n;j++){
             for(int k=;k<=n;k++){
                 if(i!=j&&j!=k){
                     if(a[i]==a[j]+a[k]){
                         cout<<i<<" "<<j<<" "<<k<<endl;
                         return ;
                     }
                 }
             }
         }
     }
     cout<<-<<endl;
 }

B

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 maxn 1000005
 typedef long long ll;
 typedef unsigned long long ull;
 /*#ifndef ONLINE_JUDGE
         freopen("1.txt","r",stdin);
 #endif */

 int a[];

 int Check(string str){
     int pre=-;
     int pos=-;
     for(int i=;i<str.length();i++){
         if(str[i]=='@'){
             pos=i;
             if(pre<i-&&i+<str.length()){
                 pre=i+;
             }
             else{
                 return -;
             }
         }
     }
     return pos;
 }

 int main(){
     #ifndef ONLINE_JUDGE
      //   freopen("1.txt","r",stdin);
     #endif
     std::ios::sync_with_stdio(false);
     string str;
     cin>>str;
     int pos=Check(str);
     if(pos!=-){
         for(int i=;i<str.length();i++){
             cout<<str[i];
             if(str[i]=='@'){

                 if(pos!=i){
                     cout<<str[i+];
                     i++;

                     if(i<str.length()-){
                         cout<<',';
                     }
                 }
             }
         }
     }
     else cout<<"No solution"<<endl;
 }

C

暴力

 #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 maxn 1000005
 typedef long long ll;
 typedef unsigned long long ull;
 /*#ifndef ONLINE_JUDGE
         freopen("1.txt","r",stdin);
 #endif */
 struct sair{
     int s,e,pos;
 }a[];

 bool cmp(sair a,sair b){
     if(a.s==b.s) return a.e<b.e;
     return a.s<b.s;
 }

 int main(){
     #ifndef ONLINE_JUDGE
      //   freopen("1.txt","r",stdin);
     #endif
     std::ios::sync_with_stdio(false);
     int n;
     cin>>n;
     for(int i=;i<n;i++){
         cin>>a[i].s>>a[i].e;
         a[i].pos=i+;
     }
     sort(a,a+n,cmp);
     vector<int>ans;
     int flag;
     for(int i=;i<n;i++){
         int pre=-;
         flag=;
         for(int j=;j<n;j++){
             if(i!=j){
                 if(pre==-){
                     pre=a[j].e;
                 }
                 else{
                     if(pre>a[j].s){
                         flag=;
                     }
                     else{
                         pre=a[j].e;
                     }
                 }
             }
         }
         if(!flag){
             ans.pb(a[i].pos);
         }
     }
     cout<<ans.size()<<endl;
     sort(ans.begin(),ans.end());
     for(int i=;i<ans.size();i++){
         cout<<ans[i]<<" ";
     }
 }

D

bfs求连通块，模拟剪纸的过程

 #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 maxn 1000005
 typedef long long ll;
 typedef unsigned long long ull;
 /*#ifndef ONLINE_JUDGE
         freopen("1.txt","r",stdin);
 #endif */

 int n,m,k;
 int book[][];
 int dir[][]={,,,,,-,-,};

 int bfs(int x,int y){
     queue<pair<int,int> >Q;
     int ans=;
     book[x][y]=;
     Q.push(make_pair(x,y));
     pair<int,int>p;
     while(!Q.empty()){
         p=Q.front();
         Q.pop();
         for(int i=;i<;i++){
             int xx=p.first+dir[i][];
             int yy=p.second+dir[i][];
             if(xx>=&&xx<=*n&&yy>=&&yy<=*m&&!book[xx][yy]){
                 book[xx][yy]=;
                 if((xx%)&&(yy%)){
                     ans++;
                 }
                 Q.push(make_pair(xx,yy));
             }
         }
     }
     return ans;
 }

 int main(){
     #ifndef ONLINE_JUDGE
         freopen("1.txt","r",stdin);
     #endif
     std::ios::sync_with_stdio(false);
     cin>>n>>m>>k;
     int a,b,c,d;
     while(k--){
         cin>>a>>b>>c>>d;///边为偶数
         a*=,b*=,c*=,d*=;
         if(a==c){
             if(b>d) swap(b,d);
             for(int i=b;i<=d;i++){
                 book[a][i]=;
             }
         }
         else{
             if(a>c) swap(a,c);
             for(int i=a;i<=c;i++){
                 book[i][b]=;
             }
         }
     }
     vector<int>ans;
     for(int i=;i<=*n;i++){
         for(int j=;j<=*m;j++){
             if(!book[i][j]&&(i%)&&(j%)){
                 ans.pb(bfs(i,j));
             }
         }
     }
     sort(ans.begin(),ans.end());
     for(int i=;i<ans.size();i++){
         cout<<ans[i]<<" ";
     }
     cout<<endl;
 }

E

题意：给2*n个数字，A和B各选n个各组成一个数，使得A+B的和最大

DP,细节在代码里

 #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 maxn 1000005
 typedef long long ll;
 typedef unsigned long long ull;
 /*#ifndef ONLINE_JUDGE
         freopen("1.txt","r",stdin);
 #endif */

 ll dp[][];
 ll p[];

 int main(){
     #ifndef ONLINE_JUDGE
       //  freopen("1.txt","r",stdin);
     #endif
     std::ios::sync_with_stdio(false);
     int n;
     string str;
     cin>>n;
     cin>>str;
     int len=*n;
     p[]=;
     for(int i=;i<=;i++){
         p[i]=p[i-]*;
     }
     ///dp[i][j] 表示A选了i个，B选了j个,dp[i][j]记录的是A+B的和
     for(int i=;i<=n;i++){
         for(int j=;j<=n;j++){
             ll tmp=str[*n-i-j]-'';///从后向前推
             if(i){
                 dp[i][j]=dp[i-][j]+tmp*p[i-];
             }
             if(j){
                 dp[i][j]=max(dp[i][j],dp[i][j-]+tmp*p[j-]);
             }
             cout<<dp[i][j]<<endl;
         }
     }
     int i=n,j=n;
     while(i||j){
         ll tmp=str[*n-i-j]-'';
         if(i>&&(tmp*p[i-]+dp[i-][j]==dp[i][j])){
             cout<<'H';
             i--;
         }
         else{
             cout<<'M';
             j--;
         }
     }
     cout<<endl;
 }