#include <bits/stdc++.h>
#define mod 1000000007
using namespace std;
stack <pair<int,int>> S;
int n,v[100005],i,dr[100005],st[100005],x,j,val,Max,nr,nr2;
long long suma[100001],total;
pair <int,int > sor[100005];
multiset<tuple<int,int,int>> s;
unsigned long long lgcput(unsigned long long b,unsigned long long p){
unsigned long long a = 1;
while(p){
if(p & 1){
a *= b;
a%=mod;
}
b*=b;
b%=mod;
p/=2;
}
return a;
}
unsigned long long cost(unsigned long long n){
return ((unsigned long long)(((unsigned long long)(n *(n+1)))%mod) *(lgcput(2,mod-2) % mod)) % mod;
}
long long rectCount(long long x, long long y){
return (cost(x) / 2 * cost(y) / 2) % mod;
}
int main()
{
ios_base::sync_with_stdio(false);
cin.tie(NULL);
cin>>n;
for(i=1;i<=n;i++){
cin>>v[i];
if(v[i] == v[i-1])
nr++;
if(v[i] >= v[i-1])
nr2++;
sor[i].first = v[i];
sor[i].second = i;
dr[i] = n + 1;
}
sort(sor+1,sor+n+1);
for(i=1;i<=n;i++){
fin>>x;
suma[i] = suma[i-1] + x;
}
for(i=1;i<=n;i++){
x = v[i];
while(S.empty() == false && x<S.top().first){
dr[S.top().second] = i;
S.pop();
}
S.push({x,i});
}
while(S.empty() == false){
S.pop();
}
for(i=n;i>=1;i--){
x = v[i];
while(S.empty() == false && x < S.top().first){
st[S.top().second] = i;
S.pop();
}
S.push({x,i});
}
for(i=1;i<=n;i++){
total += rectCount(suma[dr[sor[i].second]-1] - suma[st[sor[i].second]],sor[i].first) % mod;
for(j=1;j<=i-1;j++){
if(st[sor[j].second] <= sor[i].second && dr[sor[j].second] >= sor[i].second)
Max = sor[j].first;
}
total -= rectCount(suma[dr[sor[i].second]-1] - suma[st[sor[i].second]],Max) % mod;
}
cout << total % mod;
return 0;
}
Compilation message
fancyfence.cpp: In function 'int main()':
fancyfence.cpp:51:5: error: 'fin' was not declared in this scope; did you mean 'sin'?
51 | fin>>x;
| ^~~
| sin
