Submission #1119642

#	Time	Username	Problem	Language	Result	Execution time	Memory
1119642		squatrian	Fancy Fence (CEOI20_fancyfence)	C++17	60 / 100	106 ms	5448 KiB

fancyfence

#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
using namespace __gnu_pbds;
using namespace std;
using std::mt19937_64;
using std::random_device;
using std::uniform_int_distribution;
#include <numeric>
#define ff              first
#define ss              second
#define int             long long
#define pb              push_back
#define mp              make_pair
#define pii             pair<int,int>
#define vi              vector<int>
#define mii             map<int,int>
#define pqb             priority_queue<int>
#define pqs             priority_queue<int,vi,greater<int> >
#define setbits(x)      __builtin_popcountll(x)
#define zrobits(x)      __builtin_ctzll(x)
#define mod             1000000007
#define inf             1e18
#define ps(x,y)         fixed<<setprecision(y)<<x
#define mk(arr,n,type)  type *arr=new type[n];
mt19937                 rng(chrono::steady_clock::now().time_since_epoch().count());
 
typedef tree<int, null_type, less<int>, rb_tree_tag, tree_order_statistics_node_update> pbds;
 
 
void c_p_c()
{
    ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
#ifndef ONLINE_JUDGE
    freopen("art2.in", "r", stdin);
    freopen("art2.out", "w", stdout);
#endif
}
int dx[] = {1, -1, 0, 0};
int dy[] = {0, 0, 1, -1};
int exp(int x, int n, int m) {
    if(x == 0 and n == 0) return 1;
    x %= m; 
    int res = 1;
    while (n > 0) {
        if (n % 2 == 1) { res = res * x % m; }
        x = x * x % m;
        n /= 2;
    }
    return res;
}
int modinv(int n) {
    int r = 1;
    int p = mod - 2;
    while (p > 0) {
        if (p % 2 == 1) {
            r = (r * n) % mod;
        }
        n = (n * n) % mod;
        p /= 2;
    }
    return r;
}
int mul(int a,int b){
    return ((a*b)%mod);
}
int val(int a){
    return ((((a*(a+1))%mod)*modinv(2))%mod);
}
signed main()
{   
   int t=1;
   // c_p_c();
   // cin >> t;
   while(t--){
   int n;
   cin >> n;
   vector<int> h(n+1),w(n+1);
   for(int i = 1 ; i <= n; i++) cin >> h[i];
   for(int i = 1 ; i <= n; i++) cin >> w[i];
   stack<pair<int,int>> s;
   int ans = 0;
   for(int i = 1 ; i <= n; i++){
    if(s.empty() or s.top().ff <= h[i]){
        if(!s.empty() and s.top().ff == h[i]){
            s.top().ss = (w[i]+s.top().ss)%mod;
        }
        else{
            s.push({h[i],w[i]});
        }
    }
    else{
        int width = 0;
      while(!s.empty() and s.top().ff > h[i]){
        ans = (ans + mul(val(s.top().ff),val(width+s.top().ss)))%mod;
        ans = (ans - mul(val(s.top().ff),val(width))+mod)%mod;
        width = (width+s.top().ss)%mod;
        s.pop();
      }
      ans = (ans - mul(val(h[i]),val(width)+mod))%mod;
      if(!s.empty() and s.top().ff == h[i]){
            s.top().ss += (w[i]+width)%mod;
        }
        else{
            s.push({h[i],(w[i]+width)%mod});
        }
    }
    // cout<<ans<<endl;
   }
   int width = 0;
      while(!s.empty()){
        ans = (ans + mul(val(s.top().ff),val(width+s.top().ss)))%mod;
        ans = (ans - mul(val(s.top().ff),val(width))+mod)%mod;
        width = (width+s.top().ss)%mod;
        s.pop();
      }
      cout<<ans<<endl;

 
   }
    return 0;
}

Compilation message (stderr)

fancyfence.cpp: In function 'void c_p_c()':
fancyfence.cpp:35:12: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   35 |     freopen("art2.in", "r", stdin);
      |     ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~
fancyfence.cpp:36:12: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   36 |     freopen("art2.out", "w", stdout);
      |     ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~

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