Submission #1046176

#	Time	Username	Problem	Language	Result	Execution time	Memory
1046176		ByeWorld	Fancy Fence (CEOI20_fancyfence)	C++14	100 / 100	64 ms	24360 KiB

fancyfence

#include <bits/stdc++.h>
#pragma GCC optimize("O3")
#define int long long
#define ll long long
#define pb push_back
#define fi first
#define se second
#define lf (id<<1)
#define rg ((id<<1)|1)
#define md ((l+r)>>1)
#define ld long double
using namespace std;
typedef pair<int,int> pii;
typedef pair<int,pii> ipii;
typedef pair<ld,ld> pll;
const int MAXN = 3e5+15;
const int INF = 3e18+10;
const int MX = 2e18;
const int MOD = 1e9+7;
void chmn(int &a, int b){ a = min(a, b); }
void chsum(int &a, int b){ a%=MOD; b%=MOD; a = (a+b)%MOD; }
void chmul(int &a, int b){ a%=MOD; b%=MOD; a = (a*b)%MOD; }
int mul(int a, int b){ a%=MOD; b%=MOD; return (a*b)%MOD; }
int sum(int a, int b){ a%=MOD; b%=MOD; return (a+b)%MOD; }
int expo(int a, int b){
    if(b==0) return 1;
    int te = expo(a, b/2); te = mul(te, te);
    return (b%2 ? mul(te, a) : te);
}
mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());

int n;
int h[MAXN], w[MAXN], pr[MAXN];
int two;

struct seg {
    pii st[4*MAXN];
    void bd(int id,int l, int r){
        if(l==r){ st[id] = pii(h[l], l); return; }
        bd(lf, l, md); bd(rg, md+1, r);
        st[id] = min(st[lf], st[rg]);
    }
    pii que(int id, int l, int r, int x, int y){
        if(x<=l && r<=y) return st[id];
        if(r<x || y<l) return pii(INF, INF);
        return min(que(lf,l,md,x,y), que(rg,md+1,r,x,y));
    }
} A;
int get(int x, int y){
    return pr[y]-pr[x-1];
}
int CNT(int x, int y, int h){ // x kiri kanan, y atas bawah, h blocks di bwh
    int X = mul(mul(x, x+1), two);
    int Y = mul(mul(y, y+1), two);
    chsum(Y, mul(h, y));
    return mul(X, Y);
}

int ans;
void solve(int l, int r, int las){ // las height
    if(l>r) return;
    int mn = A.que(1,1,n,l,r).se, val = A.que(1,1,n,l,r).fi;
    chsum(ans, CNT(get(l, r), val-las, las));

    solve(l, mn-1, val); solve(mn+1, r, val);
}

signed main(){
    // ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
    cin >> n;
    two = expo(2, MOD-2);
    for(int i=1; i<=n; i++) cin >> h[i];
    A.bd(1, 1, n);
    for(int i=1; i<=n; i++){ cin >> w[i]; pr[i] = pr[i-1]+w[i]; }

    solve(1, n, 0);
    cout << ans << '\n';
}
/*
2
2 2
2 2
//30
*/

• 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