Submission #887253

#	Time	Username	Problem	Language	Result	Execution time	Memory
887253		vjudge1	Building Bridges (CEOI17_building)	C++17	30 / 100	35 ms	20112 KiB

building

#include <bits/stdc++.h>
using namespace std;
const long long INF = 1e6;
long long h[100005], w[100005], s[100005], dp[100005];
int n;
void sub1()
{
    memset(dp, 0x3f, sizeof(dp));
    dp[1] = 0;
    for(int i = 2; i <= n; ++i)
    for(int j = 1; j < i; ++j) dp[i] = min(dp[i], dp[j] + (h[i] - h[j]) * (h[i] - h[j]) + s[i - 1] - s[j]);
    cout << dp[n];
}
struct line
{
    long long a, b;
};
long long Get(line L, long long x)
{
    return L.a * x + L.b;
}
line st[4000100];
void update(int low, int high, line w, int id)
{
    if(low > high) return;
    if(low == high)
    {
        st[id] = w;
        return;
    }
    int mid = (low + high) >> 1;
    if(st[id].a > w.a) swap(st[id], w);
    if(Get(st[id], mid) > Get(w, mid))
    {
        swap(st[id], w);
        update(mid + 1, high, w, id << 1 | 1);
    }
    else update(low, mid, w, id << 1);
}
long long query(int low, int high, long long x, int id)
{
    if(low > high) return INF * INF;
    if(low == high) return Get(st[id], x);
    int mid = (low + high) >> 1;
    if(x <= mid) return min(Get(st[id], x), query(low, mid, x, id << 1));
    return min(Get(st[id], x), query(mid + 1, high, x, id << 1 | 1));
}
void full()
{
    dp[1] = 0;
    update(0, INF, {-2 * h[1], dp[1] - s[1] + h[1] * h[1]}, 1);
    for(int i = 2; i <= n; ++i)
    {
        dp[i] = query(0, INF, h[i], 1) + s[i - 1] + h[i] * h[i];
        update(0, INF, {-2 * h[i], dp[i] - s[i] + h[i] * h[i]}, 1);
    }
    cout << dp[n];
}
int main()
{
    ios_base::sync_with_stdio(0);
    cin.tie(0);
    #define Task "BRIDGES"
    if(fopen(Task".INP", "r"))
    {
        freopen(Task".INP","r",stdin);
        freopen(Task".OUT","w",stdout);
    }
    cin >> n;
    for(int i = 1; i <= n; ++i) cin >> h[i];
    for(int i = 1; i <= n; ++i)
    {
        cin >> w[i];
        s[i] = s[i - 1] + w[i];
    }
    if(n <= 1000)
    {
        sub1();
        return 0;
    }
    full();
    return 0;
}

Compilation message (stderr)

building.cpp: In function 'int main()':
building.cpp:66:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   66 |         freopen(Task".INP","r",stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~
building.cpp:67:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   67 |         freopen(Task".OUT","w",stdout);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 30 / 30
• Subtask 2: 0 / 30
• Subtask 3: 0 / 40