Submission #1025439

#	Time	Username	Problem	Language	Result	Execution time	Memory
1025439		pcc	Trains (BOI24_trains)	C++17	100 / 100	1159 ms	332492 KiB

Main

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

#pragma GCC optimize("O3,unroll-loops")
#pragma GCC target("avx2,popcnt,sse4")
#define pii pair<int,int>
#define ll long long
#define fs first
#define sc second
#define _all(T) T.begin(),T.end()
#define pll pair<ll,ll>

const int MX = 3e7+10;
const int mod = 1e9+7;
const int mxn = 1e5+10;
vector<pii> all;

int dp[mxn];
int ans[mxn];
pll arr[mxn];
int N;
int pos[mxn];
int head[mxn],nid[MX],tp[MX],idx[MX];
int ptr = 0;

void add_op(int a,int p,int id){
	ptr++;
	assert(ptr<MX);
	nid[ptr] = head[a];
	head[a] = ptr;
	tp[ptr] = p;
	idx[ptr] = id;
	return;
}

inline int mad(int a,int b){
	a += b;
	return a>=mod?a-mod:a;
}
inline int mub(int a,int b){
	a += mod-b;
	return a>=mod?a-mod:a;
}

int main(){
	ios::sync_with_stdio(0);cin.tie(0);cout.tie(0);
	cin>>N;
	for(int i = 1;i<=N;i++){
		cin>>arr[i].fs>>arr[i].sc;
		if(arr[i].fs)all.push_back(pii(arr[i].fs,i%arr[i].fs));
	}
	sort(_all(all));all.resize(unique(_all(all))-all.begin());


	for(int i = 1;i<=N;i++){
		if(!arr[i].fs)continue;
		pos[i] = lower_bound(_all(all),pii(arr[i].fs,i%arr[i].fs))-all.begin();
		ll rp = 1ll*arr[i].fs*arr[i].sc+i;
		if(rp<=N)add_op(rp,pos[i],-i);
	}
	for(int i = 0;i<all.size();i++){
		for(int j = all[i].sc;j<=N;j+=all[i].fs){
			add_op(j,i,i);
		}
	}

	if(!arr[1].fs||!arr[1].sc){
		cout<<"1\n";
		return 0;
	}
	ans[1] = 1;
	dp[pos[1]] = 1;
	for(int i = 2;i<=N;i++){
		for(int eid = head[i];eid;eid = nid[eid]){
			int p = tp[eid],id = idx[eid];
			if(id<0){
				id = -id;
				dp[p] = mub(dp[p],ans[id]);
			}
			else{
				ans[i] = mad(ans[i],dp[p]);
			}
		}
		if(arr[i].fs)dp[pos[i]] = mad(dp[pos[i]],ans[i]);
	}

	/*
	for(auto &i:all)cerr<<i.fs<<','<<i.sc<<' ';cerr<<endl;
	for(int i = 1;i<=N;i++){
		cerr<<i<<","<<ans[i]<<"::";
		for(int eid = head[i];eid;eid = nid[eid])cerr<<tp[eid]<<','<<idx[eid]<<' ';cerr<<endl;
	}
   */

	int sum = 0;
	for(int i = 1;i<=N;i++)sum = mad(sum,ans[i]);
	cout<<sum<<'\n';
	return 0;
}

Compilation message (stderr)

Main.cpp: In function 'int main()':
Main.cpp:61:17: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::pair<int, int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   61 |  for(int i = 0;i<all.size();i++){
      |                ~^~~~~~~~~~~

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