Submission #30755

#	Time	Username	Problem	Language	Result	Execution time	Memory
30755		PrOAhMeT	Boat (APIO16_boat)	C++14	9 / 100	2000 ms	4176 KiB

boat

#include <bits/stdc++.h>
#define mp make_pair
#define pb push_back
#define pii pair<int,int>
#define LL long long
#define st first
#define nd second
#define endl '\n'
using namespace std;
 
const int MAXN=505;
int dp[MAXN][MAXN*2],n,a[MAXN],b[MAXN],mod=1e9+7;
vector<int> po;
 
int main() {
 
	ios_base::sync_with_stdio(0);
	cin.tie(0);
	cin>>n;
	for(int i=1;i<=n;++i) {
		cin>>a[i]>>b[i];
		po.pb(a[i]);
		po.pb(b[i]);
		po.pb(b[i]+1);
	}
	sort(po.begin(),po.end());
	po.resize(unique(po.begin(),po.end())-po.begin());
	for(int i=1;i<=n;++i) {
		a[i]=lower_bound(po.begin(),po.end(),a[i])-po.begin();
		b[i]=lower_bound(po.begin(),po.end(),b[i])-po.begin();
	}
	for(int j=0;j<po.size();++j)
		dp[n+1][j]=1;
	for(int i=n;i>=1;--i) {
		for(int j=0;j<po.size();++j) {
			dp[i][j]=dp[i+1][j];
			for(int k=max(a[i]+1,j+1);k<=b[i]+1;++k) {
				dp[i][j]+=(1LL*(po[k]-po[k-1])*dp[i+1][k])%mod;
				if(dp[i][j]>=mod)
					dp[i][j]-=mod;
				//cout<<"doing "<<i<<" "<<k<<" "<<po[k]-po[k-1]<<" "<<dp[i+1][k]<<endl;
			}
			//cout<<i<<" "<<j<<" "<<po[j]<<" "<<dp[i][j]<<endl;
		}
	}
	cout<<(dp[1][0]-1+mod)%mod<< endl;
 
}

Compilation message (stderr)

boat.cpp: In function 'int main()':
boat.cpp:32:15: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for(int j=0;j<po.size();++j)
               ^
boat.cpp:35:16: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
   for(int j=0;j<po.size();++j) {
                ^

• Subtask 1: 9 / 9
• Subtask 2: 0 / 22
• Subtask 3: 0 / 27
• Subtask 4: 0 / 42