Submission #609478

#	Time	Username	Problem	Language	Result	Execution time	Memory
609478		SavicS	Fancy Fence (CEOI20_fancyfence)	C++17	100 / 100	69 ms	4700 KiB

fancyfence

#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
#include <bits/stdc++.h>
 
using namespace std;
using namespace __gnu_pbds;
 
typedef long long ll;
typedef long double ldb;
 
typedef pair<int,int> pii;
typedef pair<ll,ll> pll;
typedef pair<ldb,ldb> pdd;

#define ff(i,a,b) for(int i = a; i <= b; i++)
#define fb(i,b,a) for(int i = b; i >= a; i--)
#define trav(a,x) for(auto& a : x)
 
#define sz(a) (int)(a).size()
#define fi first
#define se second
#define pb push_back
#define lb lower_bound
#define ub upper_bound
#define all(a) a.begin(), a.end()
#define rall(a) a.rbegin(), a.rend()
 
mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());

template<typename T>
using ordered_set = tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>;

// os.order_of_key(k) the number of elements in the os less than k
// *os.find_by_order(k)  print the k-th smallest number in os(0-based)

const int mod = 1000000007;
const int inf = 1e9 + 5;
const int mxN = 200005; 

int n;
array<int,3> niz[mxN];

bool bio[mxN];
int pom[mxN];

int add(int a, int b){ a += b; if(a >= mod)a -= mod; return a; }
int sub(int a, int b){ a -= b; if(a < 0)a += mod; return a; }
int mul(int a, int b){ return (1ll * a * b) % mod; }
int power(int a, int b){
    if(!b)return 1;
    int p = power(a, b / 2);
    p = mul(p, p);
    if(b & 1)p = mul(p, a);
    return p;
}
int inv(int a){
    return power(a, mod - 2);
}

int len[mxN];
int par[mxN];
int L[mxN], R[mxN];
int findpar(int x){
    return (x == par[x] ? x : par[x] = findpar(par[x]));
}
void unite(int x, int y){
    x = findpar(x), y = findpar(y);
    if(x == y)return;
    par[y] = x; len[x] = add(len[x], len[y]);
    L[x] = min(L[x], L[y]); R[x] = max(R[x], R[y]);
}
void init(){
    ff(i,1,n){
        par[i] = i;
        len[i] = niz[i][1];
        L[i] = i;
        R[i] = i;
    }
}

int sum(int a){
    return mul(mul(a, a + 1), inv(2));
}

int main() {
    cin.tie(0)->sync_with_stdio(0);

    cin >> n;
    ff(i,1,n)cin >> niz[i][0], pom[i] = niz[i][0];
    ff(i,1,n)cin >> niz[i][1], niz[i][2] = i;

    init(); 

    sort(niz + 1, niz + n + 1);

    int j = n; int rez = 0;
    fb(i,n,1){
        int h = niz[i][0];

        bio[niz[i][2]] = 1;
        while(j - 1 >= 1 && niz[j - 1][0] == h){
            j -= 1; bio[niz[j][2]] = 1;
        }

        ff(l,j,i){
            int X = niz[l][2];
            if(X > 1 && bio[X - 1] == 1)unite(X - 1, X);
            if(X < n && bio[X + 1] == 1)unite(X, X + 1);
        }

        set<int> s;
        ff(l,j,i)s.insert(findpar(niz[l][2]));

        for(auto c : s){
            int l = L[c];
            int r = R[c];
            ll d = len[c];

            int mx = max(pom[l - 1], pom[r + 1]);

            int kol = mul(sum(d), sub(sum(h), sum(mx)));
            rez = add(rez, kol);

        }


        i = j;

    }

    cout << rez << '\n';

    return 0;
}
/*



// probati bojenje sahovski
*/
 
 
 
 
 

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