Submission #994965

#	Time	Username	Problem	Language	Result	Execution time	Memory
994965		salmon	Trains (BOI24_trains)	C++14	100 / 100	199 ms	249800 KiB

Main

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

vector<int> v;
map<int,long long int> mep[100100];
vector<int> rebove[100100];
int N;
long long int d,x;
vector<pair<int,int>> iv;
long long int num[100100];
long long int mod = 1'000'000'007;
const int B = 300;
long long int blom[100100][B + 5];

int main(){
	
	scanf(" %d",&N);
	
	for(int i = 0; i < N; i++){
		scanf(" %lld",&d);
		scanf(" %lld",&x);
		iv.push_back({d,x});
		num[i] = 0;
		
		if(d <= B) rebove[min((long long int)N,i + d * x)].push_back(i);
	}
	
	num[0]= 1;
	long long int sum = 0;
	
	for(int i = 0; i < N; i++){
		num[i] %= mod;
		
		for(int j : rebove[i]){
			blom[i][iv[j].first] -= num[j];
			blom[i][iv[j].first] %= mod;
		}
		
		
		if(iv[i].first <= B){
			blom[i][iv[i].first] += num[i];
			blom[i][iv[i].first] %= mod;
		}
		else{
			int d = iv[i].first;
			int x = iv[i].second;
			for(int j = 1; j <= x && i + j * d < N; j++){
				num[i + j * d] += num[i];
			}
		}
		
		for(int j = 1; j <= B; j++){
			num[min(N,i + j)] += blom[i][j];
			blom[min(N,i + j)][j] += blom[i][j];
			
			blom[min(N,i + j)][j] %= mod;
		}
		
		sum = (sum + num[i]) % mod;
	}
	
	printf("%lld",(sum + mod) % mod);
}

Compilation message (stderr)

Main.cpp: In function 'int main()':
Main.cpp:17:7: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   17 |  scanf(" %d",&N);
      |  ~~~~~^~~~~~~~~~
Main.cpp:20:8: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   20 |   scanf(" %lld",&d);
      |   ~~~~~^~~~~~~~~~~~
Main.cpp:21:8: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   21 |   scanf(" %lld",&x);
      |   ~~~~~^~~~~~~~~~~~

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