This submission is migrated from previous version of oj.uz, which used different machine for grading. This submission may have different result if resubmitted.
#include <bits/stdc++.h>
using namespace std;
const int N=501;
const int mod=1e9+7;
int n;
long long a[N],b[N],st[4*N+1];
void update(int id,int l,int r,int x,int val)
{
if(l>r||r<x||l>x) return ;
if(l==x&&r==x)
{
st[id]=val;
return ;
}
int mid=(l+r)/2;
if(mid>=x) update(id*2,l,mid,x,val);
else update(id*2+1,mid+1,r,x,val);
st[id]=(st[id*2+1]+st[id*2])%mod;
}
long long get(int id,int l,int r,int u,int v)
{
if(l>r||u>v||r<u||l>v) return 0;
if(l>=u&&v>=r) return st[id];
int mid=(l+r)/2;
return (get(id*2,l,mid,u,v)%mod+get(id*2+1,mid+1,r,u,v)%mod)%mod;
}
vector<int>v;
int main()
{
ios::sync_with_stdio(0);
cin.tie(0);
cout.tie(0);
// freopen("dut03teams.inp","r",stdin);
// freopen("dut03teams.out","w",stdout);
cin >> n;
for(int i=1;i<=n;i++)
{
cin >> a[i] >> b[i];
for(int j=a[i];j<=b[i];j++)
{
v.push_back(j);
}
}
sort(v.begin(),v.end());
int id=1;
map<int,int>mp;
for(int i=0;i<v.size();i++)
{
if(i==0||v[i]!=v[i-1])
{
mp[v[i]]=id++;
}
}
for(int i=1;i<=n;i++)
{
a[i]=mp[a[i]];
b[i]=mp[b[i]];
}
vector<long long>dp(id+1,0);
dp[0]=1;
update(1,0,n,0,1);
for(int i=1;i<=n;i++)
{
for(int j=b[i];j>=a[i];j--)
{
dp[j]=(dp[j]+get(1,0,n,0,j-1))%mod;
update(1,0,n,j,dp[j]);
}
}
long long ans=0;
for(int i=1;i<id;i++)
{
ans=(ans+dp[i])%mod;
}
cout << ans;
}
Compilation message (stderr)
boat.cpp: In function 'int main()':
boat.cpp:47:18: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
47 | for(int i=0;i<v.size();i++)
| ~^~~~~~~~~
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