Submission #887260

#	Time	Username	Problem	Language	Result	Execution time	Memory
887260		vjudge1	Building Bridges (CEOI17_building)	C++17	30 / 100	44 ms	36444 KiB

building

#include <bits/stdc++.h>

using namespace std;

#define int long long
#define MASK(x) (1 << x)

const int maxN = 1e5 + 7;
const int maxVal = (int)1e6 + 7;
const int maxLog = 31 - __builtin_clz(maxVal) + 2;
const int INF = (int)1e9 + 7;

int n, h[maxN], w[maxN];

long long psW[maxN], f1[1007], f[maxN];

struct Line {
    long long a, b;
    Line() {
        a = 0;
        b = INF;
    }
    Line(long long _a, long long _b) {
        a = _a;
        b = _b;
    }
    long long operator() (long long x) {
        return a * x + b;
    }
} node[MASK(maxLog)];

void ins(int id, int l, int r, Line L) {
    if(l > r) return;
    if(l == r) {
        node[id] = L;
        return;
    }
    int m = (l + r) >> 1;
    if(node[id].a > L.a) swap(node[id], L);
    if(node[id](m) > L(m)) {
        swap(node[id], L);
        ins(id << 1 | 1, m + 1, r, L);
    }else ins(id << 1, l, m, L);
}

void ins(Line L) {
    ins(1, 0, maxVal - 7, L);
}

long long get(int id, int l, int r, int x) {
    if(l > r) return INF;
    if(l == r) return node[id](x);
    int m = (l + r) >> 1;
    if(x <= m) return min(node[id](x), get(id << 1, l, m, x));
    return min(node[id](x), get(id << 1 | 1, m + 1, r, x));
}

long long get(int x) {
    return get(1, 0, maxVal - 7, x);
}

long long sqr(long long x) {
    return x * x;
}

void subtask1() {
    psW[0] = 0;
    for (int i = 1; i <= n; i++) {
        psW[i] = psW[i - 1] + w[i];
    }
    memset(f1, 0x3f, sizeof f1);
    f1[1] = 0;
    for (int i = 1; i <= n; i++) {
        for (int j = 1; j < i; j++) {
            f1[i] = min(f1[i], f1[j] + sqr(h[i] - h[j]) + psW[i - 1] - psW[j]);
        }
    }
    cout << f1[n] << '\n';
}

void subtask2() {
    f[1] = 0;
    for (int i = 1; i <= n; i++) {
        psW[i] = psW[i - 1] + w[i];
    }
    ins(Line(-2 * h[1], sqr(h[1]) - psW[1])); // ax + b
    for(int i = 2; i <= n; i++) {
        f[i] = get(h[i]) + sqr(h[i]) + psW[i - 1];
        ins(Line(-2 * h[i], 1ll * (f[i] - psW[i]) + sqr(h[i])));
    }
    cout << f[n] << '\n';
}

signed main() {
    cin.tie(NULL)->ios_base::sync_with_stdio(NULL);
    cin >> n;
    for (int i = 1; i <= n; i++) {
        cin >> h[i];
    }
    for (int i = 1; i <= n; i++) {
        cin >> w[i];
    }
    if (n <= 1000) subtask1();
        else subtask2();
    return 0;
}

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