Codeforces Beta Round #31 (Div. 2, Codeforces format)
http://codeforces.com/contest/31
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 maxn 1000005 8 typedef long long ll; 9 typedef unsigned long long ull; 10 /*#ifndef ONLINE_JUDGE 11 freopen("1.txt","r",stdin); 12 #endif */ 13 14 int a[105]; 15 16 int main(){ 17 #ifndef ONLINE_JUDGE 18 freopen("1.txt","r",stdin); 19 #endif 20 std::ios::sync_with_stdio(false); 21 int n; 22 cin>>n; 23 for(int i=1;i<=n;i++) cin>>a[i]; 24 for(int i=1;i<=n;i++){ 25 for(int j=1;j<=n;j++){ 26 for(int k=1;k<=n;k++){ 27 if(i!=j&&j!=k){ 28 if(a[i]==a[j]+a[k]){ 29 cout<<i<<" "<<j<<" "<<k<<endl; 30 return 0; 31 } 32 } 33 } 34 } 35 } 36 cout<<-1<<endl; 37 }
B
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 maxn 1000005 8 typedef long long ll; 9 typedef unsigned long long ull; 10 /*#ifndef ONLINE_JUDGE 11 freopen("1.txt","r",stdin); 12 #endif */ 13 14 int a[105]; 15 16 int Check(string str){ 17 int pre=-1; 18 int pos=-1; 19 for(int i=0;i<str.length();i++){ 20 if(str[i]=='@'){ 21 pos=i; 22 if(pre<i-1&&i+1<str.length()){ 23 pre=i+1; 24 } 25 else{ 26 return -1; 27 } 28 } 29 } 30 return pos; 31 } 32 33 int main(){ 34 #ifndef ONLINE_JUDGE 35 // freopen("1.txt","r",stdin); 36 #endif 37 std::ios::sync_with_stdio(false); 38 string str; 39 cin>>str; 40 int pos=Check(str); 41 if(pos!=-1){ 42 for(int i=0;i<str.length();i++){ 43 cout<<str[i]; 44 if(str[i]=='@'){ 45 46 if(pos!=i){ 47 cout<<str[i+1]; 48 i++; 49 50 if(i<str.length()-1){ 51 cout<<','; 52 } 53 } 54 } 55 } 56 } 57 else cout<<"No solution"<<endl; 58 }
C
暴力
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 maxn 1000005 8 typedef long long ll; 9 typedef unsigned long long ull; 10 /*#ifndef ONLINE_JUDGE 11 freopen("1.txt","r",stdin); 12 #endif */ 13 struct sair{ 14 int s,e,pos; 15 }a[5005]; 16 17 bool cmp(sair a,sair b){ 18 if(a.s==b.s) return a.e<b.e; 19 return a.s<b.s; 20 } 21 22 int main(){ 23 #ifndef ONLINE_JUDGE 24 // freopen("1.txt","r",stdin); 25 #endif 26 std::ios::sync_with_stdio(false); 27 int n; 28 cin>>n; 29 for(int i=0;i<n;i++){ 30 cin>>a[i].s>>a[i].e; 31 a[i].pos=i+1; 32 } 33 sort(a,a+n,cmp); 34 vector<int>ans; 35 int flag; 36 for(int i=0;i<n;i++){ 37 int pre=-1; 38 flag=0; 39 for(int j=0;j<n;j++){ 40 if(i!=j){ 41 if(pre==-1){ 42 pre=a[j].e; 43 } 44 else{ 45 if(pre>a[j].s){ 46 flag=1; 47 } 48 else{ 49 pre=a[j].e; 50 } 51 } 52 } 53 } 54 if(!flag){ 55 ans.pb(a[i].pos); 56 } 57 } 58 cout<<ans.size()<<endl; 59 sort(ans.begin(),ans.end()); 60 for(int i=0;i<ans.size();i++){ 61 cout<<ans[i]<<" "; 62 } 63 }
D
bfs求连通块，模拟剪纸的过程
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 maxn 1000005 8 typedef long long ll; 9 typedef unsigned long long ull; 10 /*#ifndef ONLINE_JUDGE 11 freopen("1.txt","r",stdin); 12 #endif */ 13 14 int n,m,k; 15 int book[505][505]; 16 int dir[4][2]={0,1,1,0,0,-1,-1,0}; 17 18 int bfs(int x,int y){ 19 queue<pair<int,int> >Q; 20 int ans=1; 21 book[x][y]=1; 22 Q.push(make_pair(x,y)); 23 pair<int,int>p; 24 while(!Q.empty()){ 25 p=Q.front(); 26 Q.pop(); 27 for(int i=0;i<4;i++){ 28 int xx=p.first+dir[i][0]; 29 int yy=p.second+dir[i][1]; 30 if(xx>=0&&xx<=2*n&&yy>=0&&yy<=2*m&&!book[xx][yy]){ 31 book[xx][yy]=1; 32 if((xx%2)&&(yy%2)){ 33 ans++; 34 } 35 Q.push(make_pair(xx,yy)); 36 } 37 } 38 } 39 return ans; 40 } 41 42 int main(){ 43 #ifndef ONLINE_JUDGE 44 freopen("1.txt","r",stdin); 45 #endif 46 std::ios::sync_with_stdio(false); 47 cin>>n>>m>>k; 48 int a,b,c,d; 49 while(k--){ 50 cin>>a>>b>>c>>d;///边为偶数 51 a*=2,b*=2,c*=2,d*=2; 52 if(a==c){ 53 if(b>d) swap(b,d); 54 for(int i=b;i<=d;i++){ 55 book[a][i]=1; 56 } 57 } 58 else{ 59 if(a>c) swap(a,c); 60 for(int i=a;i<=c;i++){ 61 book[i][b]=1; 62 } 63 } 64 } 65 vector<int>ans; 66 for(int i=1;i<=2*n;i++){ 67 for(int j=1;j<=2*m;j++){ 68 if(!book[i][j]&&(i%2)&&(j%2)){ 69 ans.pb(bfs(i,j)); 70 } 71 } 72 } 73 sort(ans.begin(),ans.end()); 74 for(int i=0;i<ans.size();i++){ 75 cout<<ans[i]<<" "; 76 } 77 cout<<endl; 78 }
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
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 maxn 1000005 8 typedef long long ll; 9 typedef unsigned long long ull; 10 /*#ifndef ONLINE_JUDGE 11 freopen("1.txt","r",stdin); 12 #endif */ 13 14 ll dp[25][25]; 15 ll p[25]; 16 17 int main(){ 18 #ifndef ONLINE_JUDGE 19 // freopen("1.txt","r",stdin); 20 #endif 21 std::ios::sync_with_stdio(false); 22 int n; 23 string str; 24 cin>>n; 25 cin>>str; 26 int len=2*n; 27 p[0]=1; 28 for(int i=1;i<=18;i++){ 29 p[i]=p[i-1]*10; 30 } 31 ///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 32 for(int i=0;i<=n;i++){ 33 for(int j=0;j<=n;j++){ 34 ll tmp=str[2*n-i-j]-'0';///从后向前推 35 if(i){ 36 dp[i][j]=dp[i-1][j]+tmp*p[i-1]; 37 } 38 if(j){ 39 dp[i][j]=max(dp[i][j],dp[i][j-1]+tmp*p[j-1]); 40 } 41 cout<<dp[i][j]<<endl; 42 } 43 } 44 int i=n,j=n; 45 while(i||j){ 46 ll tmp=str[2*n-i-j]-'0'; 47 if(i>0&&(tmp*p[i-1]+dp[i-1][j]==dp[i][j])){ 48 cout<<'H'; 49 i--; 50 } 51 else{ 52 cout<<'M'; 53 j--; 54 } 55 } 56 cout<<endl; 57 }