Submission #994689

#	Time	Username	Problem	Language	Result	Execution time	Memory
994689		LCJLY	Trains (BOI24_trains)	C++14	100 / 100	235 ms	78932 KiB

Main

#include <bits/stdc++.h>
using namespace std;
	
#define int long long 
#define ld long double
#define show(x,y) cout << y << " " << #x << endl;
#define show2(x,y,i,j) cout << y << " " << #x << "  " << j << " " << #i << endl;
#define show3(x,y,i,j,p,q) cout << y << " " << #x << "  " << j << " " << #i << "  " << q << " " << #p << endl;
#define show4(x,y) for(auto it:y) cout << it << " "; cout << #x << endl;
typedef pair<int,int>pii;
typedef pair<int,pii>pi2;

const int blk=300;
const int mod=1e9+7;

void solve(){	
	int n;
	cin >> n;
	
	int temp,temp2;
	vector<int>adj[n+5];
	int cnt[305][305];
	memset(cnt,0,sizeof(cnt));
	
	vector<int>prefix[n+5];
	vector<int>done[n+5];
	int arr[n+5];
	
	for(int x=1;x<=n;x++){
		cin >> temp >> temp2;
		arr[x]=temp;
		if(temp==0) continue;
		if(temp>=blk){
			for(int y=x+temp;y<=n;y+=temp){
				if(temp2==0) break;
				temp2--;
				adj[x].push_back(y);
			}
		}
		else{
			int hold=(n-x)/temp;
			temp2=min(temp2,hold);
			prefix[x].push_back(temp);
			prefix[x+temp2*temp].push_back(-x);
		}
	}
	
	int dp[n+5];
	memset(dp,0,sizeof(dp));
	dp[1]=1;
	for(int x=1;x<=n;x++){
		//show(x,x);
		for(int y=1;y<blk;y++){
			dp[x]=(dp[x]+cnt[x%y][y]+mod)%mod;
		}
		
		for(auto it:adj[x]){
			dp[it]=(dp[it]+dp[x])%mod;
		}
		
		for(auto it:prefix[x]){
			if(it>0){
				//show(it,it);
				cnt[x%it][it]+=dp[x];
				cnt[x%it][it]%=mod;
			}
			else{
				int hold=-it;
				//show(hold,hold);
				cnt[hold%arr[hold]][arr[hold]]-=dp[hold]-mod;
				cnt[hold%arr[hold]][arr[hold]]%=mod;
			}
		}
		//show4(dp,dp);
	}
	//show4(dp,dp);
	
	int counter=0;
	for(int x=1;x<=n;x++){
		counter=(counter+dp[x])%mod;
	}
	cout << counter;
}
 
int32_t main(){
	ios::sync_with_stdio(0);
	cin.tie(0);
	int t=1;
	//cin >> t;
	//freopen("in.txt","r",stdin);
	while(t--){
		solve();
	}
}

• Subtask 1: 8 / 8
• Subtask 2: 13 / 13
• Subtask 3: 16 / 16
• Subtask 4: 34 / 34
• Subtask 5: 29 / 29