Submission #1112566

#	Time	Username	Problem	Language	Result	Execution time	Memory
1112566		InvMOD	Building Bridges (CEOI17_building)	C++14	100 / 100	42 ms	19536 KiB

building

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

#define fi first
#define se second
#define gcd __gcd
#define sz(v) (int) v.size()
#define pb push_back
#define pi pair<int,int>
#define all(v) (v).begin(), (v).end()
#define compact(v) (v).erase(unique(all(v)), (v).end())
#define FOR(i, a, b) for(int i = (a); i <= (b); i++)
#define dbg(x) "[" #x " = " << (x) << "]"
///#define int long long

using ll = long long;
using ld = long double;
using ull = unsigned long long;

template<typename T> bool ckmx(T& a, const T& b){if(a < b) return a = b, true; return false;}
template<typename T> bool ckmn(T& a, const T& b){if(a > b) return a = b, true; return false;}

const int N = 2e5+5;
const ll MOD = 1e9+7;
const ll INF = 1e18;


struct LichaoOptMem{
    struct Line{
        ll a,b;
        Line(ll a = 0, ll b = 0): a(a), b(b) {}
        ll slope(){return a;}
        ll f(ll x){return (a == 0 && b == 0 ? LLONG_MAX : a*x + b);}
        ll intersect(Line x){return (x.b - b) / (a - x.a);}
    };

    vector<Line> st; int trsz;
    LichaoOptMem(int n = 0): st(n+1, Line()), trsz(n) {}

    void update(int l, int r, Line curLine){
        if(l > r) return;
        if(l == r){
            st[l] = (st[l].f(l) < curLine.f(l) ? st[l] : curLine);
            return;
        }
        else{
            int mid = l+r>>1;
            if(st[mid].f(mid) > curLine.f(mid)) swap(curLine, st[mid]);
            if(st[mid].slope() < curLine.slope()) update(l, mid-1, curLine);
            if(st[mid].slope() > curLine.slope()) update(mid+1, r, curLine);
        }
        return;
    }

    void addLine(ll a, ll b){
        return update(0, trsz, Line(a, b)), void();
    }

    ll query(int l, int r, ll x){
        if(l > r) return LLONG_MAX;
        if(l == r){
            return st[l].f(x);
        }
        else{
            int m = l+r>>1;
            if(x < m)
                return min(st[m].f(x), query(l, m-1, x));
            else if(x > m) return min(st[m].f(x), query(m+1, r, x));
            else return st[m].f(x);
        }
        return assert(1 == 0), 0;
    }

    ll query(ll x){
        ll val = query(0, trsz, x);
        return (val != LLONG_MAX ? val : 0);
    }
};

void solve()
{
    int n; cin >> n;

    vector<ll> h(n+1), w(n+1);
    FOR(i, 1, n) cin >> h[i];
    FOR(i, 1, n) cin >> w[i], w[i] += w[i-1];

    vector<ll> dp(n+1);
    /* Brute force
    FOR(i, 2, n){
        dp[i] = INF;
        FOR(j, 1, i-1){
            dp[i] = min(dp[i], dp[j] + (h[i] - h[j]) * (h[i] - h[j]) + (w[i-1] - w[j]));
        }
    }
    */

    LichaoOptMem lichao(*max_element(all(h)));
    FOR(i, 1, n){
        dp[i] = (i > 1 ? lichao.query(h[i]) + w[i-1] + h[i]*h[i] : 0);
        lichao.addLine(-2*h[i], h[i]*h[i] - w[i] + dp[i]);
    }

    cout << dp[n] <<"\n";
    return;
}

signed main()
{
    ios_base::sync_with_stdio(0);
    cin.tie(0);
    cout.tie(0);

    #define name "InvMOD"
    if(fopen(name".INP", "r")){
        freopen(name".INP","r",stdin);
        freopen(name".OUT","w",stdout);
    }

    int t = 1; //cin >> t;
    while(t--) solve();
    return 0;
}

Compilation message (stderr)

building.cpp: In member function 'void LichaoOptMem::update(int, int, LichaoOptMem::Line)':
building.cpp:47:24: warning: suggest parentheses around '+' inside '>>' [-Wparentheses]
   47 |             int mid = l+r>>1;
      |                       ~^~
building.cpp: In member function 'll LichaoOptMem::query(int, int, ll)':
building.cpp:65:22: warning: suggest parentheses around '+' inside '>>' [-Wparentheses]
   65 |             int m = l+r>>1;
      |                     ~^~
building.cpp: In function 'int main()':
building.cpp:116:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  116 |         freopen(name".INP","r",stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~
building.cpp:117:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  117 |         freopen(name".OUT","w",stdout);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 30 / 30
• Subtask 2: 30 / 30
• Subtask 3: 40 / 40