Submission #477154

#	Time	Username	Problem	Language	Result	Execution time	Memory
477154		LptN21	Building Bridges (CEOI17_building)	C++14	100 / 100	139 ms	127476 KiB

building

#include <bits/stdc++.h>
using namespace std;
#define fastIO ios_base::sync_with_stdio(false), cin.tie(NULL), cout.tie(NULL)
#define PI acos(-1.0)
#define FF first
#define SS second
#define eps 1e-9
// vector
#define pb push_back
#define sz(v) int((v).size())
#define all(v) (v).begin(), (v).end()
#define lb lower_bound
#define ub upper_bound
// bit
#define CNTBIT(x) __builtin_popcount(x)
#define ODDBIT(x) __builtin_parity(x)
#define MASK(i) (1ll<<(i))
#define BIT(x, i) (((x)>>(i))&1)
#define SUBSET(big, small) (((big)&(small))==(small))
#define MINBIT(x) (x)&(-x)
// typedef
typedef long long ll;
typedef unsigned long long ull;
typedef long double ld;
typedef pair<ll, ll> ii;
typedef pair<int, ii> i3;
/* CODE BELOW */
const int N=2e6+7, M=1e5+7;
const int MOD=1e9+7;
const ll oo=1e9+9;

int n, m, k, t;

int a[M];
ll p[M], _dp[M];

const ll _oo=2e18+9;

struct Line {
    ll m, b;
    Line() {m=oo, b=_oo;}
    Line(ll _m, ll _b):m(_m), b(_b) {}
    ll operator()(ll x) { return m * x + b; }
} st[N<<2];

void insert(int l, int r, Line seg, int idx=1) {
  if(l==r) {
    if(seg(l) < st[idx](l)) st[idx] = seg;
    return;
  }
  int mid= (l + r)/2, lson = idx*2, rson = idx*2+1;
  if(st[idx].m < seg.m) swap(st[idx], seg);
  if(st[idx](mid) >= seg(mid)) {
    swap(st[idx], seg);
    insert(l, mid, seg, lson);
  } else insert(mid+1, r, seg, rson);
}
ll query(int l, int r, int x, int idx=1) {
  if(l==r) return st[idx](x);
  int mid = (l + r) >> 1, lson = idx*2, rson=idx*2+1;
  if(x <= mid) return min(st[idx](x), query(l, mid, x, lson));
  else return min(st[idx](x), query(mid+1, r, x, rson));
}

signed main() {
    //freopen("test.inp", "r", stdin);
    //freopen("test.out", "w", stdout);
    //fastIO;
    scanf("%d", &n);
    for(int i=1;i<=n;i++) scanf("%d", &a[i]);
    for(int i=1;i<=n;i++) {
        scanf("%d", &m);
        p[i]=p[i-1]+m;
    }

    _dp[1]=0;
    #define sqr(x) 1LL*(x)*(x)

    insert(1, N, {-2*a[1], sqr(a[1])-p[1]});
    for(int i=2;i<=n;i++) {
        _dp[i]=sqr(a[i])-(p[i]-p[i-1])+query(1, N, a[i]);
        insert(1, N, {-2*a[i], _dp[i]+sqr(a[i])});
        //printf("%d %lld %lld _ %lld\n", i, _dp[i], query(1, N, a[i]), _dp[i]+p[i]);
    }
    printf("%lld", _dp[n]+p[n]);

    return 0;
}
/* stuff you should look for
    - int overflow, array bounds
    - special/edge cases (n=1?)
    - do smth instead of nothing and stay organized
    - WRITE STUFF DOWN
    - DONT JUST STICK ON ONE APPROACH
*/
/*  AC in real problem: https://oj.uz/problem/view/CEOI17_building
    AC in testlib LibChecker: https://judge.yosupo.jp/problem/line_add_get_min
*/

Compilation message (stderr)

building.cpp: In function 'int main()':
building.cpp:69:10: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   69 |     scanf("%d", &n);
      |     ~~~~~^~~~~~~~~~
building.cpp:70:32: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   70 |     for(int i=1;i<=n;i++) scanf("%d", &a[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", &m);
      |         ~~~~~^~~~~~~~~~

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