Submission #1266652

#	Time	Username	Problem	Language	Result	Execution time	Memory
1266652		herominhsteve	Fire (BOI24_fire)	C++20	0 / 100	0 ms	328 KiB

Main

#include <bits/stdc++.h>
#define el '\n'
#define FNAME "fire"
#define allof(x) x.begin(),x.end()
#define allof1(x) x.begin()+1,x.end()
#define mset(x,n) memset(x,(n),sizeof(x))
using namespace std;
const long long MOD = (long long) 1e9+7;
template<class X,class Y> bool minimize(X &a,Y b){ if (a>b) {a=b; return true;} return false;}
template<class X,class Y> bool maximize(X &a,Y b){ if (a<b) {a=b; return true;} return false;}

void setup(){
    ios_base::sync_with_stdio(0);
    cin.tie(0);cout.tie(0);
	if (fopen(FNAME".inp","r")){
		freopen(FNAME".inp","r",stdin);
		freopen(FNAME".out","w",stdout);
	}
}

struct Shift{
	int s,e;
	Shift(): s(0),e(0) {}
	Shift(int S,int E): s(S), e(E){}
	bool operator < (const Shift &other) const{
		return (s<other.s or (s==other.s and e<other.e));
	}
	bool isOvernight(){
		return (s>e);
	}
};

int n,m;
vector<Shift> a;

void init(){
	cin>>n>>m;
	a.resize(n);
	for (Shift &x: a) cin>>x.s>>x.e;
}

namespace Bitmask{
	void solve(){
		int MAXMASK = 1<<n;
		int res = n;
		for (int mask=1;mask<MAXMASK;mask++){
			vector<Shift> t;
			for (int i=0;i<n;i++){
				if (mask & (1<<i)){
					t.emplace_back(a[i]);
				}
			}
			sort(allof(t));
			t.emplace_back(t.front());
			int num = __builtin_popcount(mask);
			bool check=1;
			int maxE=0;
			int minS=m+1;
			int overnight=0;
			for (int i=1;i<=num;i++){
				if (t[i-1].e < t[i].s){
					check=0;
					break;
				}
				maximize(maxE,t[i].e);
				minimize(minS,t[i].s);
				if (t[i].isOvernight()) overnight=1;
			}
			if (!overnight){
				if (maxE != m) check=0;
				else if (minS!=0) check=0;
			}
			if (check) minimize(res,num);
		}
		cout<< (res==n ? -1 : res);
		exit(0);
	}
};

void sol(){
	if (n<=20) Bitmask::solve();
}

int main(){
    setup();
    init();
    sol();
}

Compilation message (stderr)

Main.cpp: In function 'void setup()':
Main.cpp:16:24: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   16 |                 freopen(FNAME".inp","r",stdin);
      |                 ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~
Main.cpp:17:24: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   17 |                 freopen(FNAME".out","w",stdout);
      |                 ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 0 / 14
• Subtask 2: 0 / 17
• Subtask 3: 0 / 9
• Subtask 4: 0 / 13
• Subtask 5: 0 / 21
• Subtask 6: 0 / 26