Codeforces Beta Round #67 (Div. 2)

Codeforces Beta Round #67 (Div. 2)

http://codeforces.com/contest/75

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);
    int a,b,c;
    cin>>a>>b;
    c=a+b;
    int ccc=0;
    int aa=0,bb=0,cc;
    int p=1;
    while(a){
        int tmp=a%10;
        if(tmp!=0){
           aa+=(tmp)*p;
           p*=10;
        }
        a/=10;
    }
    p=1;
    while(b){
        int tmp=b%10;
        if(tmp!=0){
           bb+=(tmp)*p;
           p*=10;
        }
        b/=10;
    }
    p=1;
    while(c){
        int tmp=c%10;
        if(tmp!=0){
           ccc+=(tmp)*p;
           p*=10;
        }
        c/=10;
    }
    cc=aa+bb;
    if(cc==ccc) cout<<"YES"<<endl;
    else cout<<"NO"<<endl;
}

 

B

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;


int main(){
    #ifndef ONLINE_JUDGE
     //   freopen("input.txt","r",stdin);
    #endif
    std::ios::sync_with_stdio(false);
    string me;
    cin>>me;
      int n;
    cin>>n;
      map<string,int>M,S{{"posted",15},{"commented",10},{"likes",5}};
      for(string a,b,c,x;cin>>a>>b>>c>>x;M[a],M[c])
    {
        if(c=="on")c=x,cin>>x;
        c.pop_back();c.pop_back();
        if(a==me)M[c]+=S[b];
        if(c==me)M[a]+=S[b];
      }
      vector<pair<int,string>>V;
      for(map<string,int>::iterator it=M.begin();it!=M.end();it++)V.emplace_back(-it->second,it->first);
      sort(V.begin(),V.end());
      for(int i=0;i<V.size();i++)if(V[i].second!=me)cout<<V[i].second<<endl;
}

 

C

二分+gcd 

#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 aa,bb,l,r,x,y;
int a[100005];

int main(){
    #ifndef ONLINE_JUDGE
     //   freopen("input.txt","r",stdin);
    #endif
    std::ios::sync_with_stdio(false);
    cin>>aa>>bb;
    int n;
    cin>>n;
    int gcd=__gcd(aa,bb);
    int co=1;
    int gg=sqrt(gcd);
    a[co++]=1;
    for(int i=2;i<=gg;i++){
        if(gcd%i==0){
            a[co++]=i;
            if(gcd/i!=gg){
                a[co++]=gcd/i;
            }
        }
    }
    a[co++]=gcd;
    sort(a+1,a+co);
    int mid;
    for(int i=1;i<=n;i++){
        cin>>x>>y;
        l=1,r=co-1;
        while(l<=r){
            mid=l+r>>1;
            if(a[mid]<=y) l=mid+1;
            else {
                r=mid-1;
            }
        }
        if(a[r]>y) r--;
        if(a[r]>=x&&a[r]<=y) cout<<a[r]<<endl;
        else cout<<-1<<endl;
    }
}

 

D

应该是最大子段和的加强版吧，把最大前缀和，最大后缀和，最大子区间和求出来，然后找最大值

#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 maxl[55],maxr[55],sum[55],dp[55],Right;

int main(){
    #ifndef ONLINE_JUDGE
     //   freopen("input.txt","r",stdin);
    #endif
    std::ios::sync_with_stdio(false);
    int n,m;
    cin>>n>>m;
    int num;
    int x;
    for(int i=1;i<=n;i++){
        cin>>num;
        maxl[i]=dp[i]=-0x3f3f3f3f;
        Right=0;
        for(int j=1;j<=num;j++){
            cin>>x;
            sum[i]+=x;
            maxl[i]=max(sum[i],maxl[i]);
            Right+=x;
            dp[i]=max(dp[i],Right);
            if(Right<0) Right=0;
        }
        maxr[i]=Right;
    }
    ll ans=-0x3f3f3f3f;
    Right=0;
    for(int i=1;i<=m;i++){
        cin>>x;
        ans=max(max(ans,dp[x]),Right+maxl[x]);  
        Right=max(Right+sum[x],maxr[x]);
    }
    cout<<ans<<endl;
}

 

E

几何，分类讨论即可

#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 unsigned long long ull;

struct Point{
    double x,y;
}a[105],h[105],s,e;
double ans;
int p[105],n,m;

double dis(Point a, Point b) {
    return sqrt((a.x - b.x) * (a.x - b.x) + (a.y - b.y) * (a.y - b.y));
}

double cross(Point s, Point a, Point b) {
    return (a.x - s.x) * (b.y - s.y) - (b.x - s.x) * (a.y - s.y);
}

void check(Point a, Point b, Point c, Point d, int i) {
    double t1 = cross(a, c, b), t2 = cross(a, b, d), t3 = cross(c, a, d), t4 = cross(c, d, b);
    if (fabs(t1) < eps && fabs(t2) < eps) return ;
    if (fabs(dis(a, c) + dis(c, b) - dis(a, b)) < eps) {
        h[m] = c; p[m] = i; ++m; return ;
    }
    if (t1 * t2 > eps && t3 * t4 > eps) {
        h[m].x = (t1 * d.x + t2 * c.x) / (t1 + t2);
        h[m].y = (t1 * d.y + t2 * c.y) / (t1 + t2);
        p[m] = i; ++m;
    }
}

double getl(int st, int en, int x, int y) {
    double res; st = (st + 1) % n; res = 0;
    for (int i = st; i != en; i = (i + 1) % n)
        res += dis(a[i], a[(i + 1) % n]);
    return res + dis(h[x], a[st]) + dis(a[en], h[y]);
}


int main(){
    #ifndef ONLINE_JUDGE
     //   freopen("input.txt","r",stdin);
    #endif
   // std::ios::sync_with_stdio(false);
    cin>>s.x>>s.y>>e.x>>e.y>>n;
    for (int i = 0; i < n; ++i) cin>>a[i].x>>a[i].y;
    for (int i = 0; i < n; ++i) check(s, e, a[i], a[(i + 1) % n], i);
    if (m == 2) {
        if (dis(s, h[0]) > dis(s, h[1])) swap(h[0], h[1]), swap(p[0], p[1]);
        ans = min(getl(p[0], p[1], 0, 1), getl(p[1], p[0], 1, 0));
        ans = min(ans, dis(h[0], h[1]) * 2);
        ans += dis(s, h[0]) + dis(h[1], e);
    }
    else ans = dis(s, e);
    printf("%.7f\n",ans);
}