Submission #448669

#	Time	Username	Problem	Language	Result	Execution time	Memory
448669		Khizri	Fancy Fence (CEOI20_fancyfence)	C++17	0 / 100	1 ms	332 KiB

fancyfence

#include <bits/stdc++.h>
using namespace std;
//------------------------------DEFINE------------------------------
//******************************************************************
#define IOS ios_base::sync_with_stdio(false); cin.tie(0),cout.tie(0)
#define ll long long
#define pb push_back		 
#define F first																 
#define S second 															 
#define INF 1e18
#define all(v) (v).begin(),(v).end()
#define rall(v) (v).rbegin(),(v).rend()
#define pii pair<int,int>
#define pll pair<ll,ll>
#define OK cout<<"Ok"<<endl;
#define MOD (ll)(1e9+7)
#define endl "\n"
//******************************************************************
//----------------------------FUNCTION------------------------------
//******************************************************************
ll gcd(ll a,ll b){
	if(a>b) swap(a,b);
	if(a==0) return a+b;
	return gcd(b%a,a);
}
ll lcm(ll a,ll b){
	return a/gcd(a,b)*b;
}
bool is_prime(ll n){
	ll k=sqrt(n);
	if(n==2) return true;
	if(n<2||n%2==0||k*k==n) return false;
	for(int i=3;i<=k;i+=2){
		if(n%i==0){
			return false;
		}
	}
	return true;
}
//*****************************************************************
//--------------------------MAIN-CODE------------------------------
const int mxn=2e5+5;
ll t=1,n,arr[mxn],h[mxn];
ll cal(ll k,ll sum){
	sum=sum%MOD;
	ll a=k;
	ll b=k+1;
	if(a%2==0){
		a/=2;
	}
	else{
		b/=2;
	}
	ll x=(a*b)%MOD;
	a=sum;
	b=sum+1;
	if(a%2==0){
		a/=2;
	}
	else{
		b/=2;
	}
	ll y=(a*b)%MOD;
	ll ans=(x*y)%MOD;
	return ans;
}
void solve(){
	ll ans=0;
	ll sum=0,k=0;
	cin>>n;
	bool q=true;
	for(int i=1;i<=n;i++){
		cin>>h[i];
	}
	for(int i=1;i<=n;i++){
		cin>>arr[i];
		sum+=arr[i];
	}
	stack<pll>st;
	st.push({h[1],arr[1]});
	for(int i=2;i<=n;i++){
		ll x=0;
		while(st.size()&&h[i]<st.top().F){
			ll say=cal(st.top().F,st.top().S)-cal(h[i],st.top().S);
			if(say<0){
				say+=MOD;
			}
			ans=(ans+say)%MOD;
			x+=st.top().S;
			st.pop();
		}
		st.push({h[i],x+arr[i]});
	}
	vector<pll>vt;
	while(st.size()){
		vt.pb(st.top());
		st.pop();
	}
	vt.pb({0,0});
	reverse(all(vt));
	for(int i=0;i<vt.size();i++){
		ll say=cal(vt[i].F,sum)-cal(vt[i-1].F,sum);
		if(say<0){
			say+=MOD;
		}
		ans=(ans+say)%MOD;
		sum-=vt[i].S;
	}
	cout<<ans<<endl;
}
int main(){
	IOS;
	//cin>>t;
	while(t--){
		solve();
	}
	return 0;
}

Compilation message (stderr)

fancyfence.cpp: In function 'void solve()':
fancyfence.cpp:101:15: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::pair<long long int, long long int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
  101 |  for(int i=0;i<vt.size();i++){
      |              ~^~~~~~~~~~
fancyfence.cpp:69:11: warning: unused variable 'k' [-Wunused-variable]
   69 |  ll sum=0,k=0;
      |           ^
fancyfence.cpp:71:7: warning: unused variable 'q' [-Wunused-variable]
   71 |  bool q=true;
      |       ^

• Subtask 1: 0 / 0
• Subtask 2: 0 / 12
• Subtask 3: 0 / 13
• Subtask 4: 0 / 15
• Subtask 5: 0 / 15
• Subtask 6: 0 / 18
• Subtask 7: 0 / 27