Codeforces Beta Round #34 (Div. 2)

Codeforces Beta Round #34 (Div. 2)

http://codeforces.com/contest/34

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 maxn 500005
 typedef long long ll;
 /*#ifndef ONLINE_JUDGE
         freopen("1.txt","r",stdin);
 #endif */

 int n;
 int a[];
 map<int,int>mp;

 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];
     a[n+]=a[];
     int pos1,pos2,Min=0x3f3f3f3f;
     for(int i=;i<=n;i++){
         if(abs(a[i]-a[i+])<Min){
             Min=abs(a[i]-a[i+]);
             pos1=i;
             pos2=i+;
         }
     }
     if(pos2==n+) pos2=;
     cout<<pos1<<" "<<pos2<<endl;
 }

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 maxn 500005
 typedef long long ll;
 /*#ifndef ONLINE_JUDGE
         freopen("1.txt","r",stdin);
 #endif */

 int n;
 int a[];
 map<int,int>mp;

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

C

map+vector

 #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 maxn 500005
 typedef long long ll;
 /*#ifndef ONLINE_JUDGE
         freopen("1.txt","r",stdin);
 #endif */

 map<int,int>mp;
 map<int,int>::iterator it;
 vector<int>ve;

 int main(){
     #ifndef ONLINE_JUDGE
         freopen("1.txt","r",stdin);
     #endif
     std::ios::sync_with_stdio(false);
     string str;
     cin>>str;
     int co=;
     for(int i=;i<str.length();i++){
         if(str[i]!=','){
             co=co*+str[i]-'';
         }
         else{
             mp[co]=;
             co=;
         }
     }
     mp[co]=;
     for(it=mp.begin();it!=mp.end();it++){
         ve.push_back(it->first);
     }
     ve.push_back(0x3f3f3f3f);
     sort(ve.begin(),ve.end());
     int pre=ve[];
     int flag=;
     for(int i=;i<ve.size()-;i++){
         if(ve[i+]-ve[i]!=){
             //cout<<endl<<ve[i]<<" "<<ve[i+1]<<endl;
             if(flag) cout<<',';
             if(pre!=ve[i])
                 cout<<pre<<'-'<<ve[i];
             else cout<<pre;
             pre=ve[i+];
             if(!flag){
                 flag=;
             }
         }
     }
 }

D

题意不好理解，是要求树换一个根结点后的前驱

 #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 maxn 500005
 typedef long long ll;
 /*#ifndef ONLINE_JUDGE
         freopen("1.txt","r",stdin);
 #endif */

 vector<int>ve[];
 int r1,r2;
 int n;
 int ans[];
 int vis[];

 void dfs(int pos){
     vis[pos]=;
     for(int i=;i<ve[pos].size();i++){
         if(!vis[ve[pos][i]]){
             ans[ve[pos][i]]=pos;
             dfs(ve[pos][i]);
         }
     }
 }

 int main(){
     #ifndef ONLINE_JUDGE
        // freopen("1.txt","r",stdin);
     #endif
     std::ios::sync_with_stdio(false);
     cin>>n>>r1>>r2;
     int a;
     for(int i=;i<=n;i++){
         if(i!=r1){
             cin>>a;
             ve[i].push_back(a);
             ve[a].push_back(i);
         }
     }
     dfs(r2);
     for(int i=;i<=n;i++){
         if(i!=r2){
             cout<<ans[i]<<" ";
         }
     }
 }