Submission #393995

#	Time	Username	Problem	Language	Result	Execution time	Memory
393995		jeqcho	Boat (APIO16_boat)	C++17	0 / 100	4 ms	4300 KiB

boat

#include <bits/stdc++.h>
using namespace std;

typedef long long ll;
typedef pair<int,int> pii;
typedef vector<int> vi;
typedef vector<pair<int,int>> vpi;

#define FOR(i,a,b) for (int i = (a); i < (b); ++i)
#define F0R(i,a) FOR(i,0,a)
#define ROF(i,a,b) for (int i = (b)-1; i >= (a); --i)
#define R0F(i,a) ROF(i,0,a)
#define trav(a,x) for (auto& a: x)

#define pb push_back
#define rsz resize
#define sz(x) int(x.size())
#define all(x) begin(x), end(x)
#define fi first
#define se second

int const N=5e2+3;
int const A=1e3+3;
int a[N],b[N];
ll unzip[A];
ll dp[N][A];
ll mod =1e9+7;

ll asum(ll n, ll a1=1, ll d=1)
{
	return n*(2*a1+(n-1)*d)/2;
}

int main()
{
	ios_base::sync_with_stdio(0); cin.tie(0);
	int n;
	cin>>n;
	set<int> st;
	F0R(i,n)
	{
		cin>>a[i]>>b[i];
		st.insert(a[i]);
		st.insert(b[i]);
	}
	int idx=1;
	map<int,int> mp;
	trav(e,st)
	{
		mp[e]=idx;
		unzip[idx]=e;
		++idx;
	}
	F0R(i,n)
	{
		a[i]=mp[a[i]];
		b[i]=mp[b[i]];
	}
	fill(dp[0],dp[0]+A,0);
	dp[0][0]=1;
	F0R(i,n)
	{
		fill(dp[i+1],dp[i+1]+A,0);
		ll sum=0;
		F0R(j,b[i]+1)
		{
			
			if(j>a[i])
			{
				dp[i+1][j]=sum*(asum(unzip[j]-unzip[j-1])%mod);
				dp[i+1][j]+=dp[i][j];
				dp[i+1][j]%=mod;
			}
			else if(j==a[i])
			{
				dp[i+1][j]=sum+dp[i][j];
				dp[i+1][j]%=mod;
			}
			else
			{
				dp[i+1][j]=dp[i][j];
			}
			sum+=dp[i][j];
			sum%=mod;
			
			
		}
		
	}
	ll ans=0;
	FOR(j,1,A)
	{
		ans+=dp[n][j];
		ans%=mod;
	}
	cout<<ans<<'\n';
	return 0;
}

• Subtask 1: 0 / 9
• Subtask 2: 0 / 22
• Subtask 3: 0 / 27
• Subtask 4: 0 / 42