#include <bits/stdc++.h> using namespace std; #define endl '\n' #define st first #define nd second #define pb push_back #define sz(x) (int)(x).size() #define all(x) (x).begin(), (x).end() #define ll long long ll mod=1000000007; int inf=1000000007; ll infl=1000000000000000007; int p[1000007]; int a[1000007]; int n; int calc(int m,int k,int l,int r) { if(k<0) return 0; if(m+k>n) return 0; int d=r-l+1; k-=d-m; if(k<0) return 0; int mn=min(l-1,n-r),mx=max(l-1,n-r); return max(0,min(k,mn)-max(0,(k-mx))+1); } int main() { ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0); cin>>n; for(int i=1;i<=n;i++) { cin>>a[i]; p[a[i]]=i; } int l=p[n],r=p[n]; ll ans=0; for(int i=1;i<=n;i++) { l=min(l,p[n-i+1]); r=max(r,p[n-i+1]); ans+=(ll)calc(i,i-1,l,r); ans+=(ll)calc(i,i-2,l,r); // cout<<l<<" "<<r<<endl; } cout<<2*n+1<<" "<<ans; return 0; }
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 | #include <bits/stdc++.h> using namespace std; #define endl '\n' #define st first #define nd second #define pb push_back #define sz(x) (int)(x).size() #define all(x) (x).begin(), (x).end() #define ll long long ll mod=1000000007; int inf=1000000007; ll infl=1000000000000000007; int p[1000007]; int a[1000007]; int n; int calc(int m,int k,int l,int r) { if(k<0) return 0; if(m+k>n) return 0; int d=r-l+1; k-=d-m; if(k<0) return 0; int mn=min(l-1,n-r),mx=max(l-1,n-r); return max(0,min(k,mn)-max(0,(k-mx))+1); } int main() { ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0); cin>>n; for(int i=1;i<=n;i++) { cin>>a[i]; p[a[i]]=i; } int l=p[n],r=p[n]; ll ans=0; for(int i=1;i<=n;i++) { l=min(l,p[n-i+1]); r=max(r,p[n-i+1]); ans+=(ll)calc(i,i-1,l,r); ans+=(ll)calc(i,i-2,l,r); // cout<<l<<" "<<r<<endl; } cout<<2*n+1<<" "<<ans; return 0; } |