Submission #320686

#	Time	Username	Problem	Language	Result	Execution time	Memory
320686		phathnv	Building Bridges (CEOI17_building)	C++11	100 / 100	125 ms	9956 KiB

building

#include <bits/stdc++.h>

#define mp make_pair
#define X first
#define Y second

using namespace std;

typedef long long ll;
typedef pair <int, int> ii;

const int N = 1e5 + 1;
const ll INF = 1e18;

struct line{
    ll a, b;
    line(ll _a = 0, ll _b = 0){
        a = _a;
        b = _b;
    }
    ll y(int x){
        return a * x + b;
    }
};

struct segmentTree{
    line d[N * 4];
    int x[N];
    void build(int id, int l, int r, int _x[]){
        d[id] = line(0, INF);
        if (l == r){
            x[l] = _x[l];
            return;
        }
        int mid = (l + r) >> 1;
        build(id << 1, l, mid, _x);
        build(id << 1 | 1, mid + 1, r, _x);
    }
    void addLine(int id, int l, int r, line val){
        if (val.y(x[l]) >= d[id].y(x[l]) && val.y(x[r]) >= d[id].y(x[r]))
            return;
        if (val.y(x[l]) <= d[id].y(x[l]) && val.y(x[r]) <= d[id].y(x[r])){
            d[id] = val;
            return;
        }
        int mid = (l + r) >> 1;
        addLine(id << 1, l, mid, val);
        addLine(id << 1 | 1, mid + 1, r, val);
    }
    ll getMin(int id, int l, int r, int pos){
        if (pos < l || r < pos)
            return INF;
        ll res = d[id].y(x[pos]);
        if (l == r)
            return res;
        int mid = (l + r) >> 1;
        res = min(res, getMin(id << 1, l, mid, pos));
        res = min(res, getMin(id << 1 | 1, mid + 1, r, pos));
        return res;
    }
} ST;

int n, h[N], w[N];
int x[N], nX;
ll s[N];

void readInput(){
    scanf("%d", &n);
    for(int i = 1; i <= n; i++)
        scanf("%d", &h[i]);
    for(int i = 1; i <= n; i++)
        scanf("%d", &w[i]);
}

void solve(){
    for(int i = 1; i <= n; i++){
        s[i] = s[i - 1] + w[i];
        x[i] = h[i];
    }
    sort(x + 1, x + 1 + n);
    nX = unique(x + 1, x + 1 + n) - (x + 1);

    ll res = 0;
    ST.build(1, 1, nX, x);
    ST.addLine(1, 1, nX, line(-2 * h[1], (ll) h[1] * h[1] - s[1]));
    for(int i = 2; i <= n; i++){
        int pos = lower_bound(x + 1, x + 1 + nX, h[i]) - x;
        res = ST.getMin(1, 1, nX, pos) + (ll) h[i] * h[i] + s[i - 1];
        ST.addLine(1, 1, nX, line(-2 * h[i], res + (ll) h[i] * h[i] - s[i]));
    }
    printf("%lld", res);
}

int main(){
    readInput();
    solve();
    return 0;
}

Compilation message (stderr)

building.cpp: In function 'void readInput()':
building.cpp:68:10: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   68 |     scanf("%d", &n);
      |     ~~~~~^~~~~~~~~~
building.cpp:70:14: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   70 |         scanf("%d", &h[i]);
      |         ~~~~~^~~~~~~~~~~~~
building.cpp:72:14: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   72 |         scanf("%d", &w[i]);
      |         ~~~~~^~~~~~~~~~~~~

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