Codeforces Beta Round #25 (Div. 2 Only)
http://codeforces.com/contest/25
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 maxn 500005 7 typedef long long ll; 8 /*#ifndef ONLINE_JUDGE 9 freopen("1.txt","r",stdin); 10 #endif */ 11 12 int n; 13 int a[105]; 14 map<int,int>mp; 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 int d=0,s=0; 24 int posd,poss; 25 for(int i=1;i<=n;i++){ 26 cin>>a[i]; 27 if(a[i]%2) d++,posd=i; 28 else s++,poss=i; 29 } 30 if(d>s) cout<<poss<<endl; 31 else cout<<posd<<endl; 32 33 }
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 maxn 500005 7 typedef long long ll; 8 /*#ifndef ONLINE_JUDGE 9 freopen("1.txt","r",stdin); 10 #endif */ 11 12 int n; 13 int a[105]; 14 map<int,int>mp; 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 string str; 24 cin>>str; 25 int co=0; 26 while(n){ 27 if(n>3){ 28 n-=2; 29 cout<<str[co]<<str[co+1]<<'-'; 30 co+=2; 31 } 32 else{ 33 if(n==3) 34 cout<<str[co]<<str[co+1]<<str[co+2]<<endl; 35 else 36 cout<<str[co]<<str[co+1]<<endl; 37 n=0; 38 } 39 } 40 }
C
用floyd跑，类似DP的思想
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 maxn 500005 7 typedef long long ll; 8 /*#ifndef ONLINE_JUDGE 9 freopen("1.txt","r",stdin); 10 #endif */ 11 12 ll dp[305][305]; 13 14 int main(){ 15 #ifndef ONLINE_JUDGE 16 freopen("1.txt","r",stdin); 17 #endif 18 //std::ios::sync_with_stdio(false); 19 int n; 20 cin>>n; 21 for(int i=0;i<n;i++){ 22 for(int j=0;j<n;j++){ 23 cin>>dp[i][j]; 24 } 25 } 26 int m; 27 cin>>m; 28 ll u,v,c; 29 while(m--){ 30 cin>>u>>v>>c; 31 u--,v--; 32 ll ans=0; 33 for(int i=0;i<n;i++){ 34 for(int j=0;j<n;j++){ 35 dp[i][j]=min(dp[i][j],min(dp[i][u]+c+dp[v][j],dp[i][v]+c+dp[u][j])); 36 ans+=dp[i][j]; 37 } 38 } 39 cout<<ans/2<<" "; 40 } 41 }
D
并查集，判断是否成环，成环的话把可以构成环的边删去并找到另一个集合把他们连起来
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 maxn 500005 7 typedef long long ll; 8 /*#ifndef ONLINE_JUDGE 9 freopen("1.txt","r",stdin); 10 #endif */ 11 12 int fa[1005]; 13 14 int Find(int x){ 15 int r=x,y; 16 while(x!=fa[x]){ 17 x=fa[x]; 18 } 19 while(r!=x){ 20 y=fa[r]; 21 fa[r]=x; 22 r=y; 23 } 24 return x; 25 } 26 27 bool join(int x,int y){ 28 int xx=Find(x); 29 int yy=Find(y); 30 if(xx!=yy){ 31 fa[xx]=yy; 32 return true; 33 } 34 return false; 35 } 36 37 int main(){ 38 #ifndef ONLINE_JUDGE 39 freopen("1.txt","r",stdin); 40 #endif 41 //std::ios::sync_with_stdio(false); 42 int n; 43 cin>>n; 44 int u,v; 45 vector<pair<int,int> >ve; 46 for(int i=0;i<=1001;i++) fa[i]=i; 47 for(int i=1;i<n;i++){ 48 cin>>u>>v; 49 if(!join(u,v)) ve.push_back(make_pair(u,v)); 50 } 51 vector<pair<pair<int,int>,pair<int,int> > >ans; 52 for(int i=0;i<ve.size();i++){ 53 u=ve[i].first; 54 for(int j=1;j<=n;j++){ 55 if(join(u,j)){ 56 ans.push_back(make_pair(make_pair(u,ve[i].second),make_pair(u,j))); 57 break; 58 } 59 } 60 } 61 cout<<ans.size()<<endl; 62 for(int i=0;i<ans.size();i++){ 63 cout<<ans[i].first.first<<" "<<ans[i].first.second<<" "<<ans[i].second.first<<" "<<ans[i].second.second<<endl; 64 } 65 }
E
字符串hash 找到一个前缀和另一个后缀最长相同的长度，也可以用kmp做
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 maxn 500005 7 typedef long long ll; 8 typedef unsigned long long ull; 9 const ull MOD=257; 10 /*#ifndef ONLINE_JUDGE 11 freopen("1.txt","r",stdin); 12 #endif */ 13 int Check(string s1,string s2){ 14 int len=0; 15 if(s1.find(s2)!=-1) return s1.length(); 16 if(s2.find(s1)!=-1) return s2.length(); 17 int len1=s1.length(); 18 int len2=s2.length(); 19 int ans=len1+len2; 20 int i=len1-1,j=0; 21 ull aa=0,bb=0; 22 ull flag=1; 23 // cout<<s1<<" "<<s2<<endl; 24 while(i>=0&&j<len2){ 25 aa=s1[i]*flag+aa; 26 flag=flag*MOD; 27 bb=bb*MOD+s2[j]; 28 // cout<<s1[i]<<" "<<s2[j]<<" "<<aa<<" "<<bb<<endl; 29 if(aa==bb){ 30 len=j+1; 31 } 32 i--,j++; 33 } 34 return ans-len; 35 } 36 37 int main(){ 38 #ifndef ONLINE_JUDGE 39 freopen("1.txt","r",stdin); 40 #endif 41 //std::ios::sync_with_stdio(false); 42 string s1,s2,s3; 43 cin>>s1>>s2>>s3; 44 int len1=s1.length(),len2=s2.length(),len3=s3.length(); 45 // cout<<len1<<" "<<len2<<" "<<len3<<" "<<len1+len2+len3<<endl; 46 int ans=0x3f3f3f3f; 47 ans=min(ans,(Check(s1,s2)+Check(s2,s3)-len2)); 48 ans=min(ans,Check(s1,s3)+Check(s3,s2)-len3); 49 ans=min(ans,Check(s2,s1)+Check(s1,s3)-len1); 50 ans=min(ans,Check(s2,s3)+Check(s3,s1)-len3); 51 ans=min(ans,Check(s3,s1)+Check(s1,s2)-len1); 52 ans=min(ans,Check(s3,s2)+Check(s2,s1)-len2); 53 cout<<ans<<endl; 54 }