Codeforces Round #654 (Div. 2) E - Asterism 二分

E1

#include<cstdio>
#include<cstring>
#include<iostream>
#include<algorithm>
#include<map>
using namespace std;
#define int long long
const int N=1e6+10;
int a[N];
int b[N];
int n;
int p;
int sum[N];
bool check(int x)
{
    int ans=1;
    for(int i=1;i<=n;i++)
    {
        ans=(ans*(sum[x]-i+1))%p;
        x++;
        if(ans==0)
            return false;
    }
    return 1;
}
void solve()
{
    
    cin>>n>>p;
    map<int,int>mp;
    for(int i=1;i<=n;i++)
        cin>>a[i],mp[a[i]]++;
    for(int i=1;i<=5000;i++)
        sum[i]=sum[i-1]+mp[i];
    vector<int>v;
    for(int i=1;i<=2020;i++)
        if(check(i))
            v.push_back(i);
    cout<<v.size()<<endl;
    for(auto x:v)
        cout<<x<<" ";
    cout<<endl;
            
}
signed main()
{
    int t=1;
    while(t--)
        solve();
}

E2

#include<map>
#include<queue>
#include<time.h>
#include<limits.h>
#include<cmath>
#include<ostream>
#include<iterator>
#include<set>
#include<stack>
#include<cstdio>
#include<cstring>
#include<iostream>
#include<algorithm>
using namespace std;
#define rep_1(i,m,n) for(int i=m;i<=n;i++)
#define mem(st) memset(st,0,sizeof st)
inline int read()
{
    int num=0, w=0;
    char ch=0;
    while (!isdigit(ch))
    {
        w|=ch=='-';
        ch = getchar();
    }
    while (isdigit(ch))
    {
        num = (num<<3) + (num<<1) + (ch^48);
        ch = getchar();
    }
    return w? -num: num;
}
typedef long long ll;
typedef pair<int,int> pii;
typedef unsigned long long ull;
typedef pair<double,double> pdd;
const int inf = 0x3f3f3f3f;
const int N=2e6+10;
int n,k;
int tot;
int a[N];
int X[N]; 
int b[N];
int pre[N];
map<int,int>p;
inline bool jud(int x)
{
    int tmp=upper_bound(b+1,b+tot+1,x)-b-1;
    int nw=pre[tmp];
    //如果大于等于k,那么往后必定会*k
    //如果是0,那么就说明之前没有人可以战胜，就不行
    if(nw>=k||nw==0)
        return false;
    for(int i=1; i<=n-1; i++)
    {
        nw--;
        x++;
        nw+=p[x];
        //可以选择的个数
        if(nw>=k||nw==0)
            return false;
    }
    return true;
}
void solve()
{
    cin>>n>>k;
    for(int i=1; i<=n; i++)
        a[i]=read(),p[a[i]]++,b[i]=a[i];
    sort(a+1,a+n+1);
    sort(b+1,b+n+1);
    tot=unique(b+1,b+n+1)-b-1;//离散化之后的个数
    for(int i=1; i<=n; i++)
    {
        int tmp=lower_bound(b+1,b+tot+1,a[i])-b;
        X[tmp]++;//离散化之后的
    }
    for(int i=1; i<=tot; i++)
        pre[i]=pre[i-1]+X[i];
    int l=max(a[1],a[n]-n+1),r=a[n],ans=0;
    for(int i=1; i<=n; i++)
        l=max(l,a[i]-i+1);
    int x=l;
    while(l<=r)
    {
        int mid=(l+r)>>1;
        if(jud(mid))
            ans=mid,l=mid+1;
        else
            r=mid-1;
    }
    cout<<max(ans-x+1,0)<<endl;
    for(int i=x; i<=ans; i++)
        cout<<i<<" ";
    cout<<endl;
}
int main()
{
    int t=1;
    while(t--)
        solve();
    return 0;
}