Submission #362460

#	Time	Username	Problem	Language	Result	Execution time	Memory
362460		Bill_00	Remittance (JOI19_remittance)	C++14	15 / 100	1 ms	512 KiB

remittance

#include <bits/stdc++.h>
#define pb push_back
#define ff first
#define ss second
#define M 1000001
typedef long long ll;
const int p=53;
const long long MOD=1000000007;
using namespace std;
ll a[M],b[M],c[M],d[M],n;
ll pow2[M];
ll power(ll a,ll b){
	ll res=1;
	while(b>0){
		if(b&1){
			res=res*a;
			if(res>=MOD) res%=MOD;
		}
		b>>=1;
		a=a*a;
		if(a>=MOD) a%=MOD;
	}
	return res;
}
ll turn(ll k){
	return (k+10*MOD)%MOD;
}
ll suma,sumb,sumgiven;
int main(){
	ios_base::sync_with_stdio(0);
	cin.tie(0);
	cout.tie(0);
	cin >> n;
	pow2[0]=1;
	for(int i=1;i<=n;i++){
		pow2[i]=pow2[i-1]*2;
		if(pow2[i]>=MOD) pow2[i]%=MOD;
	}
	for(int i=0;i<n;i++){
		cin >> a[i] >> b[i];
		suma+=a[i];
		sumb+=b[i];
		c[i]=a[i]-b[i];
	}
	long long res=0;
	for(int i=1;i<n;i++){
		res+=((turn(c[i])*pow2[i-1])%MOD);
		if(res>=MOD) res%=MOD;
	}
	bool f=0;	
	res+=((c[0]*pow2[n-1])%MOD);
	if(res>=MOD) res%=MOD;
	res=res*power(pow2[n]-1,MOD-2);
	if(res>=MOD) res%=MOD;
	d[0]=res;
	sumgiven=d[0];
	for(int i=1;i<n;i++){
		ll e=c[i]+d[i-1];
		if(e&1){
			cout << "No";
			return 0;
		}
		d[i]=e/2;
		sumgiven+=(d[i]);
		if(d[i]<0){
			cout << "No";
			return 0;
		}
		if(d[i-1]+a[i]<2*d[i]){
			cout << "No";
			return 0;
		}
		if(a[i]>=2*d[i]) f=1;
	}
	if(d[n-1]+a[0]<2*d[0]){
		cout << "No";
		return 0;
	}
	if(c[0]-2*d[0]+d[n-1]!=0){
		cout << "No";
		return 0;
	}
	if(sumgiven+sumb!=suma){
		cout << "No";
		return 0;
	}
	int last=-1,i=0,p=0,o=0;
	bool flag=0;
	while(1){
		ll e=a[i]/2;
		e=min(e,d[i]);
		if(i==n-1) a[0]+=e;
		else a[i+1]+=e;
		a[i]-=(2*e);
		d[i]-=e;
		if(d[i]==0){
			flag=1;
		}
		if(d[i]>0 && flag==1){
			cout << "No";
			return 0;
		}
		if(d[i]>0 && (a[i]<=1)) o++;
		else o=0;
		if(d[i]==0) p++;
		else p=0;
		if(p==n){
			cout << "Yes";
			return 0;
		}
		if(o==n){
			cout << "No";
			return 0;
		}
		if(i==n-1) i=0;
		else i++;
	}
}

Compilation message (stderr)

remittance.cpp: In function 'int main()':
remittance.cpp:50:7: warning: variable 'f' set but not used [-Wunused-but-set-variable]
   50 |  bool f=0;
      |       ^
remittance.cpp:87:6: warning: unused variable 'last' [-Wunused-variable]
   87 |  int last=-1,i=0,p=0,o=0;
      |      ^~~~

• Subtask 1: 15 / 15
• Subtask 2: 0 / 40
• Subtask 3: 0 / 45