Submission #993031

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Source Code Expand

#pragma GCC optimize("O3")
#pragma GCC target("sse4.2")

#include <vector>
#include <queue>
#include <unordered_map>
#include <tuple>
#include <cstdio>
#include <cmath>
using namespace std;

namespace std{
	template<typename T>
	inline void hash_combine(size_t& seed, T const& v){
		seed ^= hash<T>()(v) + 0x9e3779b9 + (seed<<6) + (seed>>2);
	}
	template<typename It>
	inline size_t hash_range(It first, It last){
		size_t seed=0;
		hash_range(seed,first,last);
		return seed;
	}
	template<typename It>
	inline void hash_range(size_t& seed, It first, It last){
		for(;first!=last;++first)hash_combine(seed, *first);
	}
	template<typename A,typename B>
	class hash<pair<A,B>>{
		public:
		size_t operator()(pair<A,B> const &p) const{
			size_t seed=0;
			hash_combine(seed,p.first);
			hash_combine(seed,p.second);
			return seed;
		}
	};
}

int main(){
	long long N,A,R;
	scanf("%lld%lld",&N,&A);R=N;
	if(N>1000000)return 1;
	if(N>10000)R=sqrt(R);

	unordered_map<pair<long long,long long>,long long>m; //m<n,speed>=time
	m[{0,1}]=0;
	priority_queue<tuple<long long,long long,long long> >q;
	q.push(make_tuple(0,0,1));
	for(;!q.empty();){
		auto cur=q.top();q.pop();
		long long time=-get<0>(cur);
		long long n=get<1>(cur);
		long long speed=get<2>(cur);
		
		if(time>=R)continue;

		vector<tuple<int,int,int>> nxt={
			make_tuple(0,n,time+A),
			make_tuple(n+speed,speed,time+1)
		};
		for(auto &e:nxt){
			long long nxtn=get<0>(e);
			long long nxtspeed=get<1>(e);
			long long nxttime=get<2>(e);
			if(nxtn>=N){
				R=min(R,nxttime);
			}else if(nxttime<R && (m.find({nxtn,nxtspeed})==m.end()||m[{nxtn,nxtspeed}]>nxttime)){
				m[{nxtn,nxtspeed}]=nxttime;
				q.push(make_tuple(-nxttime,nxtn,nxtspeed));
			}
		}
	}
	printf("%lld\n",R);
}

Submission Info

Compile Error

./Main.cpp: In function ‘int main()’:
./Main.cpp:41:25: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result]
  scanf("%lld%lld",&N,&A);R=N;
                         ^

Judge Result