Submission #1138021

#	Time	Username	Problem	Language	Result	Execution time	Memory
1138021		why1	Trains (BOI24_trains)	C++20	37 / 100	2096 ms	5192 KiB

Main

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

#define ll long long
#define pb push_back
#define pii pair<int,int>
#define sz size()
#define all(v) v.begin(),v.end()
#define fi first
#define se second

const int N = 2e5;
const int mod = 1e9+7;
const int INF = 1e9;

const int di[] = {1, -1, 0, 0};
const int dj[] = {0, 0, 1, -1};

ll t[4*N],modify[4*N];

void push(int v,int l,int r) {
    if(modify[v]!=0 and v+v+1<4*N) {
        modify[v+v]+=modify[v];
        modify[v+v+1]+=modify[v];
		modify[v+v]%=mod;
		modify[v+v+1]%=mod;
        int mid=(l+r)/2;
        t[v+v]+=(mid-l+1)*1ll*modify[v];
        t[v+v+1]+=(r-mid)*1ll*modify[v];
		t[v+v]%=mod;
		t[v+v+1]%=mod;
        modify[v]=0;
    }
}
 
void upd(int v,int l,int r,int rl,int rr,ll x) {
    if(r<rl or rr<l)
        return;
    if(rl<=l and r<=rr) {
        t[v]+=(r-l+1)*x;
        modify[v]+=x;
		t[v]%=mod;
		modify[v]%=mod;
        return;
    }
    push(v,l,r);
    int mid=(l+r)/2;
    upd(v+v,l,mid,rl,rr,x);
    upd(v+v+1,mid+1,r,rl,rr,x);
    t[v]=(t[v+v]+t[v+v+1])%mod;
}

int get(int v,int l,int r,int pos){
	if(l==r)
		return t[v];
	else{
		push(v,l,r);
		int mid=(l+r)/2;
		if(pos<=mid)
			return get(v+v,l,mid,pos);
		else
			return get(v+v+1,mid+1,r,pos);
	}
}

void solve() {
	int n;
	cin>>n;
	int d[n+1],x[n+1];
	bool check=1;
	for(int i = 1; i <= n; i++){
		cin>>d[i]>>x[i];
		if(d[i]!=1)
			check=0;
	}	
	if(check){
		upd(1,1,n,1,1,1);
		for(int i = 1; i <= n; i++){
			if(x[i]>0){
				ll val=get(1,1,n,i)%mod;
				upd(1,1,n,i+1,i+x[i],val);
			}
		}
		ll ans=0;
		for(int i = 1; i <= n; i++){
			ans=(ans+get(1,1,n,i))%mod;
		}
		cout<<ans<<"\n";
		return;
	}
	ll dp[n+1];
	memset(dp,0,sizeof(dp));
	dp[1]=1;
	for(int i = 2; i <= n; i++){
		for(int j = 1; j < i; j++){
			if(d[j]==0)
				continue;
			int k=(i-j)/d[j];
			if(i%d[j]==j%d[j] && 1<=k && k<=x[j]){
				dp[i]=(dp[i]+dp[j])%mod;
			}
		}
	}
	ll ans=0;
	for(int i = 1; i <= n; i++){
		ans=(ans+dp[i])%mod;
	}
	cout<<ans<<"\n";
}

int main() {

	//freopen("cowrun.in","r",stdin);
	//freopen("cowrun.out","w",stdout);

    ios_base::sync_with_stdio(false);
    cin.tie(nullptr);
    cout.tie(nullptr);

	int t=1;
	//cin>>t;
	while(t--) {
        solve();
	}

    return 0;
}

• Subtask 1: 8 / 8
• Subtask 2: 13 / 13
• Subtask 3: 16 / 16
• Subtask 4: 0 / 34
• Subtask 5: 0 / 29