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[105];
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=1;i<=n;i++) cin>>a[i];
    a[n+1]=a[1];
    int pos1,pos2,Min=0x3f3f3f3f;
    for(int i=1;i<=n;i++){
        if(abs(a[i]-a[i+1])<Min){
            Min=abs(a[i]-a[i+1]);
            pos1=i;
            pos2=i+1;
        }
    }
    if(pos2==n+1) pos2=1;
    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[105];
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=1;i<=n;i++) cin>>a[i];
    sort(a+1,a+n+1);
    int ans=0;
    for(int i=1;i<=n&&m;i++){
        if(a[i]<0){
            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=0;
    for(int i=0;i<str.length();i++){
        if(str[i]!=','){
            co=co*10+str[i]-'0';
        }
        else{
            mp[co]=1;
            co=0;
        }
    }
    mp[co]=1;
    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[0];
    int flag=0;
    for(int i=0;i<ve.size()-1;i++){
        if(ve[i+1]-ve[i]!=1){
            //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+1];
            if(!flag){
                flag=1;
            }
        }
    }
}

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[50005];
int r1,r2;
int n;
int ans[50005];
int vis[50005];

void dfs(int pos){
    vis[pos]=1;
    for(int i=0;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=1;i<=n;i++){
        if(i!=r1){
            cin>>a;
            ve[i].push_back(a);
            ve[a].push_back(i);
        }
    }
    dfs(r2);
    for(int i=1;i<=n;i++){
        if(i!=r2){
            cout<<ans[i]<<" ";
        }
    }
}