Submission #1279659

#	Time	Username	Problem	Language	Result	Execution time	Memory
1279659		trandangquang	Fancy Fence (CEOI20_fancyfence)	C++20	27 / 100	18 ms	2264 KiB

fancyfence

#include<bits/stdc++.h>
using namespace std;

#define foru(i,a,b) for(int i=(a); i<=(b); ++i)
#define ford(i,a,b) for(int i=(a); i>=(b); --i)
#define rep(i,a) for(int i=0; i<(a); ++i)
#define sz(a) (int)(a).size()
#define all(a) (a).begin(),(a).end()
#define bit(s,i) (((s)>>(i))&1)
#define ii pair<int,int>
#define fi first
#define se second
#define pb push_back
#define eb emplace_back
#define ll long long
#define _ << " " <<

template <class X, class Y> bool maxi(X &x, Y y){return x<y?x=y,true:false;}
template <class X, class Y> bool mini(X &x, Y y){return x>y?x=y,true:false;}

const int N=1e5+5;
const int mod=1e9+7;

int n,h[N],w[N],l[N],r[N],pw[N];

int div2(int x){
    if(x%2==0) return x/2;
    return (x+mod)/2;
}
int choose(int x){
    return (div2(1LL*x*(x-1)%mod) + x) % mod;
}
int calc(int hh, int ww){
    return 1LL*choose(hh)*choose(ww) % mod;
}

void solve(){
    cin>>n;
    foru(i,1,n) cin>>h[i];
    foru(i,1,n) cin>>w[i];

    foru(i,1,n){
        l[i]=i-1;
        while(l[i]>0 && h[l[i]]>h[i]) l[i]=l[l[i]];
    }
    ford(i,n,1){
        r[i]=i+1;
        while(r[i]<=n && h[r[i]]>=h[i]) r[i]=r[r[i]];
    }
    foru(i,1,n){
        pw[i]=(pw[i-1]+w[i]) % mod;
    }

    int res=0;
    foru(i,1,n){
        int totw=(pw[r[i]-1]-pw[l[i]]+mod)%mod;
        res=(res + calc(h[i],totw) - calc(max(h[l[i]],h[r[i]]),totw) + mod) % mod;
    }
    cout<<res<<'\n';
}

int32_t main(){
    #define task "test"
    if(fopen(task".inp","r")){
        freopen(task".inp","r",stdin);
        freopen(task".out","w",stdout);
    }
    cin.tie(0)->sync_with_stdio(0);

    int tc=1; //cin>>tc;
    rep(i,tc){
        solve();
    }
}

Compilation message (stderr)

fancyfence.cpp: In function 'int32_t main()':
fancyfence.cpp:65:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   65 |         freopen(task".inp","r",stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~
fancyfence.cpp:66:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   66 |         freopen(task".out","w",stdout);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 0 / 0
• Subtask 2: 12 / 12
• Subtask 3: 0 / 13
• Subtask 4: 15 / 15
• Subtask 5: 0 / 15
• Subtask 6: 0 / 18
• Subtask 7: 0 / 27