結果

問題 No.2438 Double Least Square
ユーザー 👑 Nachia
提出日時 2023-08-19 00:08:22
言語 C++17
(gcc 13.3.0 + boost 1.87.0)
結果
AC  
実行時間 314 ms / 2,000 ms
コード長 2,717 bytes
コンパイル時間 1,374 ms
コンパイル使用メモリ 93,644 KB
最終ジャッジ日時 2025-02-16 11:07:19
ジャッジサーバーID
(参考情報)
judge3 / judge5
このコードへのチャレンジ
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ファイルパターン 結果
sample AC * 3
other AC * 30
権限があれば一括ダウンロードができます

ソースコード

diff #
プレゼンテーションモードにする

#include <iostream>
#include <string>
#include <vector>
#include <algorithm>
#include <atcoder/modint>
using namespace std;
using i32 = int;
using u32 = unsigned int;
using i64 = long long;
using u64 = unsigned long long;
#define rep(i,n) for(int i=0; i<(int)(n); i++)
const i64 INF = 1001001001001001001;
using Modint = atcoder::static_modint<998244353>;
int main(){
int N; cin >> N;
int H; cin >> H;
double h = (double)H / 2;
vector<double> X(N), Y(N);
rep(i,N) cin >> X[i] >> Y[i];
vector<int> I(N); rep(i,N) I[i] = i;
rep(i,N) Y[i] -= h;
sort(I.begin(), I.end(), [&](int l, int r) -> bool {
return X[l] * Y[r] - X[r] * Y[l] > 0;
});
rep(t,2){
vector<double> F(N);
rep(i,N) F[i] = X[I[i]];
swap(X, F);
swap(X, Y);
}
auto XI = X;
XI.push_back(0.0);
sort(XI.begin(), XI.end());
double ans = 1e100;
auto xxx = [](double xx, double xy, double yy){
return (xx == 0.0) ? 0.0 : (yy - xy*xy/xx);
};
for(double xc : XI){
vector<double> XX0(N+1), XY0(N+1), YY0(N+1);
vector<double> XX1(N+1), XY1(N+1), YY1(N+1);
vector<double> f(N+1);
rep(t,2){
vector<double> X0, X1, Y0, Y1;
rep(i,N){
if(X[i] <= xc){
X0.push_back(X[i]);
X1.push_back(0);
Y0.push_back(Y[i]+h);
Y1.push_back(0);
} else {
X0.push_back(0);
X1.push_back(X[i]);
Y0.push_back(0);
Y1.push_back(Y[i]+h);
}
}
if(t){ swap(X0,X1); swap(Y0,Y1); }
rep(i,N) XX0[i+1] = XX0[i] + X0[i] * X0[i];
for(int i=N-1; i>=0; i--) f[i] = f[i+1] + X1[i] * X1[i];
rep(i,N+1) XX0[i] += f[i];
rep(i,N) XY0[i+1] = XY0[i] + X0[i] * Y0[i];
for(int i=N-1; i>=0; i--) f[i] = f[i+1] + X1[i] * Y1[i];
rep(i,N+1) XY0[i] += f[i];
rep(i,N) YY0[i+1] = YY0[i] + Y0[i] * Y0[i];
for(int i=N-1; i>=0; i--) f[i] = f[i+1] + Y1[i] * Y1[i];
rep(i,N+1) YY0[i] += f[i];
swap(XX0,XX1); swap(XY0,XY1); swap(YY0,YY1);
h = -h;
}
for(int s=0; s<=N; s++){
double c0 = xxx(XX0[s],XY0[s],YY0[s]);
double c1 = xxx(XX1[s],XY1[s],YY1[s]);
ans = min(ans, c0 + c1);
}
}
cout.precision(10);
fixed(cout);
cout << ans << endl;
return 0;
}
struct ios_do_not_sync{
ios_do_not_sync(){
ios::sync_with_stdio(false);
cin.tie(nullptr);
}
} ios_do_not_sync_instance;
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