Submission #49889

#	Time	Username	Problem	Language	Result	Execution time	Memory
49889		hamzqq9	Boat (APIO16_boat)	C++14	100 / 100	1296 ms	3304 KiB

boat

#include<bits/stdc++.h>
#define lf double
#define ll long long
#define cc pair<char,char>
#define ull unsigned ll
#define ii pair<int,int>
#define li pair<ll,int>
#define iii pair<int,ii>
#define iiii pair<ii,ii>
#define iiii2 pair<int,iii>
#define lii pair<ll,ii>
#define lolo pair<ll,ll>
#define heap priority_queue
#define mp make_pair
#define st first
#define nd second
#define pb push_back
#define pf push_front
#define ppb pop_back
#define ppf pop_front
#define all(x) x.begin(),x.end()
#define len(x) strlen(x)
#define sz(x) (int) x.size()
#define orta ((bas+son)/2)
#define min3(x,y,z) min(min(x,y),z)
#define max3(x,y,z) max(max(x,y),z)
#define umin(x,y) x=min(x,y)
#define umax(x,y) x=max(x,y)
#define dbgs(x) cerr<<(#x)<<" --> "<<(x)<<" "
#define dbg(x) cerr<<(#x)<<" --> "<<(x)<<endl;getchar()
#define MOD 1000000007
#define inf 100000000
#define M 10000002
#define N 1005
#define LOG 20
#define magic 100
#define KOK 250
#define EPS 0.0025
#define pw(x) ((1ll)<<(x))
#define PI 3.1415926535
using namespace std;

int n,cev;
int a[N],b[N],dp[N][N],inv[N];
vector<ii> seg,e;

int add(int x,int y) {

	x+=y;

	while(x<0) x+=MOD;
	while(x>=MOD) x-=MOD;

	return x;

}

int mul(int x,int y) {

	return 1ll*x*y%MOD;

}

int fe(int x,int y) {

	if(y==0) return 1;
	if(y==1) return x;

	int res=fe(x,y/2);

	res=mul(res,res);

	if(y&1) res=mul(res,x);

	return res;

}

int main() {
 
 	#if 0
	freopen("input.txt","r",stdin);
 	#endif

	for(int i=1;i<N;i++) {

		inv[i]=fe(i,MOD-2);

	}

	scanf("%d",&n);

	for(int i=1;i<=n;i++) {

		scanf("%d %d",&a[i],&b[i]);

		e.pb({a[i],0});
		e.pb({b[i],1});

	}

	sort(all(e));

	seg.pb({-inf,e[0].st-1});

	for(int i=0;i<sz(e)-1;i++) {

		int x=e[i].st+e[i].nd,y=e[i+1].st-!e[i+1].nd;

		if(x>y) continue ;

		seg.pb({x,y});

	}

	seg.pb({e.back().st+1,inf});

	//for(auto ss:seg) printf("%d %d\n",ss.st,ss.nd);

	for(int i=0;i<sz(seg);i++) dp[0][i]=1;

	for(int i=1;i<=n;i++) {

		int flag=0;

		for(int now=0;now<sz(seg);now++) {

			ii rng=seg[now];

			if(rng.st>b[i] || rng.nd<a[i]) {
			
				if(now) {

					dp[i][now]=dp[i][now-1];

				}

				continue ;
			
			}

			int tot=0;
			int sz=rng.nd-rng.st+1;
			int res=sz;
			int ans=0;

			for(int j=i-1;j>=0;j--) {

				ans=add(ans,mul(res,dp[j][now-1])); 

				if(rng.st>=a[j] && rng.nd<=b[j]) {

					tot++;

					res=mul(res,sz+tot);

					res=mul(res,inv[tot+1]);

				}
			
			}

			cev=add(cev,ans);

			dp[i][now]=add(dp[i][now-1],ans);

			//printf("RESULT : %d %d %d\n",i,now,ans);

		}

	}

	printf("%d",cev);

}

Compilation message (stderr)

boat.cpp: In function 'int main()':
boat.cpp:124:7: warning: unused variable 'flag' [-Wunused-variable]
   int flag=0;
       ^~~~
boat.cpp:91:7: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  scanf("%d",&n);
  ~~~~~^~~~~~~~~
boat.cpp:95:8: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   scanf("%d %d",&a[i],&b[i]);
   ~~~~~^~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 9 / 9
• Subtask 2: 22 / 22
• Subtask 3: 27 / 27
• Subtask 4: 42 / 42