Submission #528080

#	Time	Username	Problem	Language	Result	Execution time	Memory
528080		idas	Fancy Fence (CEOI20_fancyfence)	C++11	100 / 100	44 ms	5380 KiB

fancyfence

#include <bits/stdc++.h>
#define FAST_IO ios_base::sync_with_stdio(0); cin.tie(nullptr); cout.tie(nullptr)
#define FOR(i, begin, end) for(int i = (begin); i < (end); i++)
#define TSTS int ttt; cin >> ttt; while(ttt--) solve()
#define all(x) (x).begin(), (x).end()
#define le(vec) vec[vec.size()-1]
#define sz(x) ((int)((x).size()))
#define pb push_back
#define s second
#define f first

using namespace std;
typedef long long ll;
typedef long double ld;
typedef vector<int> vi;
typedef map<int, int> mii;
typedef pair<int, int> pii;
typedef pair<long long, long long> pll;
typedef pair<long double, long double> pdd;

const int INF=1e9, MOD=1e9+7, mod=998244353;
const ll LINF=1e18;

void setIO()
{
    FAST_IO;
}

void setIO(string s)
{
    FAST_IO;
    freopen((s+".in").c_str(), "r", stdin);
    freopen((s+".out").c_str(), "w", stdout);
}

const int N=1e5+10;
ll h[N], w[N];
int n, par[N];
bool v[N];

int fnd(int u)
{
    return par[u]=par[u]==u?u:fnd(par[u]);
}

void mrg(int a, int b)
{
    a=fnd(a); b=fnd(b);
    if(a==b) return;
    w[a]+=w[b];
    w[a]%=MOD;
    par[b]=a;
}

ll eq(ll x)
{
    return (x+1)*x/2%MOD;
}

ll eval(ll x, ll y)
{
    return eq(x)*eq(y)%MOD;
}

bool cmp(int a, int b)
{
    return h[a]>h[b];
}

int main()
{
    setIO();
    cin >> n;
    vi idx;
    FOR(i, 0, n) cin >> h[i], idx.pb(i);
    FOR(i, 0, n) cin >> w[i];

    sort(all(idx), cmp);

    FOR(i, 0, n) par[i]=i;

    ll ans=0;
    for(auto i : idx){
        v[i]=true;
        ll x=0, y=0;
        if(i!=0){
            if(v[i-1]){
                x=w[fnd(i-1)];
            }
        }
        if(i!=n-1){
            if(v[i+1]){
                y=w[fnd(i+1)];
            }
        }

        ans+=eval(h[i], w[i]+x+y);
        ans-=eval(h[i], x);
        ans-=eval(h[i], y);
        while(ans<0) ans+=MOD;
        ans%=MOD;

        if(x!=0) mrg(i, i-1);
        if(y!=0) mrg(i, i+1);
    }

    cout << ans;
}

Compilation message (stderr)

fancyfence.cpp: In function 'void setIO(std::string)':
fancyfence.cpp:32:12: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   32 |     freopen((s+".in").c_str(), "r", stdin);
      |     ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
fancyfence.cpp:33:12: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   33 |     freopen((s+".out").c_str(), "w", stdout);
      |     ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

• 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