delete pics to save space

2.1635.cpp

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+#include<iostream>
+#include<cmath>
+#include<cstring>
+#include<vector>
+using namespace std;
+const int maxn=100005;
+int useable[maxn];
+void get_primes(int n,vector<int> &primes)
+{
+	int m=int(sqrt(n)+0.5);
+	for(int i=2;i<=m;i++)
+		if(n%i==0)
+		{
+			primes.push_back(i);
+			while(n%i==0) n/=i;
+		}
+	if(n>1) primes.push_back(n);
+}
+int main()
+{
+#ifdef local
+	freopen("pro.in","r",stdin);
+#endif
+	int n,m,kase=0;
+	while(cin>>n>>m)
+	{
+		vector<int> primes;
+		get_primes(m,primes);
+		memset(useable,0,sizeof(useable));
+		n--;
+		for(int i=0;i<primes.size();i++)
+		{
+			int p=primes[i],e=0;//C(n,0) = p^e
+			int min_e=0,x=m;
+			while(x%p==0) {x/=p; min_e++;}
+			//C(n,k)=C(n,k-1)*(n-k+1)/k
+			for(int k=1;k<n;k++)
+			{
+				x=n-k+1;
+				while(x%p==0) {x/=p; e++;}
+				x=k;
+				while(x%p==0) {x/=p; e--;}
+				if(e<min_e) useable[k]=1;
+			}
+		}
+		vector<int> res;
+		for(int k=1;k<n;k++)
+			if(!useable[k]) res.push_back(k+1);
+		cout<<res.size()<<"\n";
+		if(!res.empty())
+		{
+			cout<<res[0];
+			for(int i=1;i<res.size();i++) cout<<' '<<res[i];
+		}
+		cout<<"\n";
+	}
+	return 0;
+}