Codeforces Beta Round #72 (Div. 2 Only)

Codeforces Beta Round #72 (Div. 2 Only)

http://codeforces.com/contest/84

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 eb emplace_back
 #define maxn 1000006
 #define eps 1e-8
 #define pi acos(-1.0)
 #define rep(k,i,j) for(int k=i;k<j;k++)
 typedef long long ll;
 typedef unsigned long long ull;
 int main(){
     #ifndef ONLINE_JUDGE
      //   freopen("input.txt","r",stdin);
     #endif
     std::ios::sync_with_stdio(false);
     ll n;
     cin>>n;
     cout<<*n-n/<<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 pb push_back
 #define eb emplace_back
 #define maxn 1000006
 #define eps 1e-8
 #define pi acos(-1.0)
 #define rep(k,i,j) for(int k=i;k<j;k++)
 typedef long long ll;
 typedef unsigned long long ull;

 int n;
 ll a[];

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

C

 #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 eb emplace_back
 #define maxn 1000006
 #define eps 1e-8
 #define pi acos(-1.0)
 #define rep(k,i,j) for(int k=i;k<j;k++)
 typedef long long ll;
 typedef unsigned long long ull;

 const int N = , D = ;
 int n, m, x, y, c[N], r[N], s[N];
 vector<int> v[D *  + ];

 int main(){
     #ifndef ONLINE_JUDGE
      //   freopen("input.txt","r",stdin);
     #endif
     std::ios::sync_with_stdio(false);
     cin>>n;
     int ans=;
     for (int i = ; i <= n; i++){
         cin>>c[i]>>r[i];
         c[i] += D; s[i] = -;
         for (int j = c[i] - r[i]; j <= c[i] + r[i]; j++) v[j].push_back(i);
     }
     cin>>m;
     for (int i = ; i <= m; i++){
         cin>>x>>y;
         x += D;
         for (auto j : v[x]) if (s[j] == -)
             if (y * y + (x - c[j]) * (x - c[j]) <= r[j] * r[j]){
                 s[j] = i;
                 ans++;
             }
     }
     cout<<ans<<endl;
     for (int i = ; i <= n; i++) cout<<s[i]<<" ";
 }

D

二分+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 eb emplace_back
 #define maxn 1000006
 #define eps 1e-8
 #define pi acos(-1.0)
 #define rep(k,i,j) for(int k=i;k<j;k++)
 typedef long long ll;
 typedef unsigned long long ull;

 ll a[];
 ll n,k;
 int book[];
 vector<int>ans;

 bool erfen(ll mid){
     ll sum=;
     for(int i=;i<=n;i++){
         sum+=min(a[i],mid);
     }
     if(sum>=k) return true;
     return false;
 }

 int main(){
     #ifndef ONLINE_JUDGE
      //   freopen("input.txt","r",stdin);
     #endif
     std::ios::sync_with_stdio(false);
     cin>>n>>k;
     ll sum=;
     ll Max=;
     ll L,R,mid;
     for(int i=;i<=n;i++){
         cin>>a[i];
         sum+=a[i];
         Max=max(Max,a[i]);
     }
     if(sum<k) cout<<-<<endl;
     else if(sum==k){}
     else{
         L=,R=Max,mid;
         while(L<=R){
             mid=L+R>>;
             if(erfen(mid)){
                 R=mid-;
             }
             else{
                 L=mid+;
             }
         }
         ll kk=R;
         sum=;
         for(int i=;i<=n;i++){
             sum+=min(a[i],kk);
             a[i]-=min(a[i],kk);
         }
         int flag=;
         for(int i=;i<=n;i++){
             if(sum>k&&a[i]>){
                 book[i]=;
                 ans.pb(i);
             }
             else if(a[i]>){
                 sum++;
                 a[i]--;
                 if(sum>k&&flag&&a[i]>=){
                     flag=;
                     ans.pb(i);
                     book[i]=;
                 }
             }

         }
         for(int i=;i<=n;i++){
             if(!book[i]&&a[i]>){
                 book[i]=;
                 ans.pb(i);
             }
         }
         for(int i=;i<ans.size();i++){
             cout<<ans[i]<<" ";
         }
     }

 }

E

__builtin_popcount() 函数，计算一个数转二进制之后有几个1

一道很好的最短路的题目。

题意：求S到T的最短路径，其中，路径上不同的字母不能超过K个，且答案的字典序要最小，不存在输出-1

思路：因为K小于等于4,所以可以用状压来存放不同字母的个数。在优先队列中存放距离，路径的字符串，K和该点的下表，跑一次最短路即可。

 #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 eb emplace_back
 #define maxn 1000006
 #define eps 1e-8
 #define pi acos(-1.0)
 #define rep(k,i,j) for(int k=i;k<j;k++)
 typedef long long ll;
 typedef pair<int,int> pii;
 typedef pair<pair<int,string>,pii> ppp;
 typedef unsigned long long ull;

 int n,m,k;
 int S,T;
 string s[];
 set<pii>se;

 int dist(int a,int b){
     return abs(a/m-b/m)+abs(a%m-b%m);
 }

 int dir[][]={,,,,,-,-,};

 void Dijstra(){
     priority_queue<ppp,vector<ppp>,greater<ppp>>Q;
     Q.push({{dist(S,T),""},{,S}});
     ppp ss;
     string str;
     int book,pos;
     int x,y,xx,yy;
     while(!Q.empty()){
         ss=Q.top();
         Q.pop();
         str=ss.first.second;
         book=ss.second.first;
         pos=ss.second.second;
         if(!se.count({book,pos})){
             se.insert({book,pos});
             x=pos/m,y=pos%m;
             for(int i=;i<;i++){
                 xx=x+dir[i][];
                 yy=y+dir[i][];
                 if(xx>=&&xx<n&&yy>=&&yy<m){
                     if(s[xx][yy]=='T'){
                         cout<<str<<endl;
                         exit();
                     }
                     if(__builtin_popcount(book|(<<(s[xx][yy]-'a')))<=k)
                         Q.push({{dist(xx*m+yy,T)+str.length()+,str+s[xx][yy]},{book|(<<(s[xx][yy]-'a')),xx*m+yy}});
                 }
             }
         }
     }

 }

 int main(){
     #ifndef ONLINE_JUDGE
      //   freopen("input.txt","r",stdin);
     #endif
     std::ios::sync_with_stdio(false);
     cin>>n>>m>>k;
     for(int i=;i<n;i++){
         cin>>s[i];
         for(int j=;j<m;j++){
             if(s[i][j]=='S'){
                 S=i*m+j;
             }
             if(s[i][j]=='T'){
                 T=i*m+j;
             }
         }
     }
     Dijstra();
     cout<<-<<endl;
 }