#include<bits/stdc++.h>
#define ll long long
#define pii pair<ll,ll>
#define fi first
#define se second
using namespace std;
int const mod=1e9+7;
map<int,int> index;
vector<int> val;
vector<int> fen(1010,0);
void upd(int idx,int val)
{
idx+=2;
for(int i=idx;i<1010;i+=i&-i)fen[i]+=val,fen[i]%=mod;
}
int qr(int idx)
{
idx+=2;
int ret=0;
for(int i=idx;i>0;i-=i&-i)ret+=fen[i],ret%=mod;
return ret;
}
int pow(int a,int b)
{
if(b==0)return 1;
if(b==1)return a;
int ret=pow(a,b/2);
if(b%2==0)return (ret*ret)%mod;
else return (((ret*ret)%mod)*a)%mod;
}
map<int,int> inverse;
int inv(int a)
{
if(inverse[a]!=0)return inverse[a];
inverse[a]=pow(a,mod-2);
return inverse[a];
}
int choose(int a,int b)
{
if(b>a)return 0;
int ret=1;
for(int i=b+1;i<=a;i++)
{
ret*=i;
ret%=mod;
}
for(int i=2;i<=a-b;i++)
{
ret*=inv(i);
ret%=mod;
}
return ret;
}
signed main()
{
int n;
cin>>n;
vector<pii> info;
set<int> temp;
for(int i=0;i<n;i++)
{
int a,b;
cin>>a>>b;
temp.insert(a);
temp.insert(b+1);
info.push_back({a,b+1});
}
for(auto it:temp)
{
val.push_back(it);
index[it]=val.size()-1;
//cout<<it<<" "<<index[it]<<endl;
}
vector<vector<int>> pre(510,vector<int>(1010,-2));
vector<int> latest(1010,-1);
for(int i=0;i<n;i++)
{
for(int j=index[info[i].fi];j<index[info[i].se];j++)
{
pre[i][j]=latest[j];
latest[j]=i;
}
}
upd(-1,1);
vector<vector<int>> dp(510,vector<int>(1010,0));
for(int i=0;i<n;i++)
{
//cout<<endl<<i<<":";
for(int j=index[info[i].se]-1;j>=index[info[i].fi];j--)
{
//cout<<j<<" ";
int a=qr(j),b=(val[j+1]-val[j]);
dp[i][j]=a;
int ans=a*b;
ans%=mod;
int bef=pre[i][j],k=2;
while(bef!=-1)
{
ans+=dp[bef][j]*choose(b,k);
ans%=mod;
bef=pre[bef][j];
k++;
}
upd(j+1,ans);
//cout<<i<<" "<<j<<" "<<ans<<endl;
}
}
cout<<(qr(1005)+mod-1)%mod;
return 0;
}
Compilation message
boat.cpp:8:14: error: 'std::map<int, int> index' redeclared as different kind of entity
8 | map<int,int> index;
| ^~~~~
In file included from /usr/include/string.h:432,
from /usr/include/c++/10/cstring:42,
from /usr/include/x86_64-linux-gnu/c++/10/bits/stdc++.h:48,
from boat.cpp:1:
/usr/include/strings.h:61:1: note: previous declaration 'const char* index(const char*, int)'
61 | index (const char *__s, int __c) __THROW
| ^~~~~
boat.cpp: In function 'int main()':
boat.cpp:71:14: error: invalid types '<unresolved overloaded function type>[int]' for array subscript
71 | index[it]=val.size()-1;
| ^
boat.cpp:78:24: error: invalid types '<unresolved overloaded function type>[long long int]' for array subscript
78 | for(int j=index[info[i].fi];j<index[info[i].se];j++)
| ^
boat.cpp:78:44: error: invalid types '<unresolved overloaded function type>[long long int]' for array subscript
78 | for(int j=index[info[i].fi];j<index[info[i].se];j++)
| ^
boat.cpp:89:24: error: invalid types '<unresolved overloaded function type>[long long int]' for array subscript
89 | for(int j=index[info[i].se]-1;j>=index[info[i].fi];j--)
| ^
boat.cpp:89:47: error: invalid types '<unresolved overloaded function type>[long long int]' for array subscript
89 | for(int j=index[info[i].se]-1;j>=index[info[i].fi];j--)
| ^
