Lưu ý: Các code mẫu dưới đây chỉ mang tính tham khảo và có thể không AC được bài tập này

Code mẫu của flashmt

#include <iostream>
#include <algorithm>
#include <cstdio>
#include <vector>
#include <utility>
#include <cmath>
#define fr(a,b,c) for (a=b;a<=c;a++)
#define N 100100
using namespace std;

int n,m,P,X[N];
long long re = -1LL << 60;
double Left[N];
vector < pair<long long,long long> > line,poly;

void Convex_Hull()
{
    int i;
    double x=-1e18;
    sort(line.begin(),line.end());
    fr(i,0,m-1)
        if (!i || line[i].first!=line[i-1].first)
        {
            long long A=-line[i].first,B=line[i].second;
            while (P>1)
            {
                long long AA=poly[P-1].first,BB=poly[P-1].second;
                x=1.0*(B-BB)/(AA-A);
                if (x>Left[P-1]) break;
                poly.pop_back(); P--;
            }
            if (P)
            {
                long long AA=poly[P-1].first,BB=poly[P-1].second;
                x=1.0*(B-BB)/(AA-A);
            }
            poly.push_back(make_pair(A,B)); Left[P++]=x;
        }
}

void Query(int x)
{
    int low=0,high=P-1,pos;
    while (low<=high)
    {
        int mid=(low+high)/2;
        if (Left[mid]<=x) pos=mid, low=mid+1;
        else high=mid-1;
    }
    re=max(re,1LL*x*x+poly[pos].first*x+poly[pos].second);
}

int main()
{
    int y0,i,x,y;
    cin >> n >> y0;
    fr(i,1,n) scanf("%d",&X[i]);
    cin >> m;
    fr(i,1,m)
    {
        scanf("%d%d",&x,&y);
        y-=y0;
        line.push_back(make_pair(2LL*x,1LL*x*x+1LL*y*y));
    }
    Convex_Hull();
    fr(i,1,n) Query(X[i]);
    printf("%.6lf\n",sqrt(re));
    return 0;
}

Code mẫu của happyboy99x

#include<iostream>
#include<iomanip>
#include<cstring>
#include<cmath>
using namespace std;

const int N = 1e5;
bool hasGirl[N + 1];
int x[N], y[N], d[N + 1], n, m, Y0;

void enter() {
    cin >> n >> Y0;
    for(int i = 0; i < n; ++i) {
        int x; cin >> x;
        hasGirl[x] = true;
    }
    cin >> m;
    for(int i = 0; i < m; ++i)
        cin >> x[i] >> y[i];
}

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

bool check(double maxDist) {
    memset(d, 0, sizeof d);
    for(int i = 0; i < m; ++i) {
        double temp = sqrt(sqr(maxDist) - sqr(y[i] - Y0));
        if(temp != temp) continue;
        int iTemp = (int) temp;
        ++d[max(0, x[i] - iTemp)];
        if(x[i] + iTemp + 1 <= N) --d[x[i] + iTemp + 1];
    }
    for(int i = 0; i <= N; ++i) {
        if(i > 0) d[i] += d[i - 1];
        if(hasGirl[i] && d[i] == 0) return false;
    }
    return true;
}

void solve() {
    double low = 0, high = 1e6;
    for(int iter = 0; iter < 50; ++iter) {
        double mid = (low + high) / 2;
        if(check(mid)) high = mid;
        else low = mid;
    }
    cout << fixed << setprecision(6) << low << endl;
}

int main() {
    ios::sync_with_stdio(false);
    enter();
    solve();
    return 0;
}

Code mẫu của ladpro98

#include <bits/stdc++.h>
#define X first
#define Y second
#define sqr(a) ((a) * (a))

using namespace std;

typedef pair<long long, long long> point;

const int N = 100005;
const long long INF = (long long)1e12;

point a[N];
int cut[N], cnt[N];
int x[N], Y0;
int n, m;

long long dist(point P, int x) {
    return sqr(P.X - x) + sqr(P.Y - Y0);
}

void genTest() {
    srand(time(NULL));
    ofstream fout; fout.open("KTOUR.txt");
    int n = 1000, Y0 = 0, m = 1000, LIM = 100000;
    fout << n << ' ' << Y0 << '\n';
    for (int i = 1; i <= n; ++i) fout << rand() % LIM << ' '; fout << endl;
    fout << m << '\n';
    for (int i = 1; i <= m; ++i) fout << rand() % LIM << ' ' << rand() % LIM << endl;
    fout.close();
}

void naive() {
    long long ans = 0;
    for (int i = 1; i <= n; ++i) {
        long long minDist = INF;
        for (int j = 1; j <= m; ++j)
            minDist = min(minDist, dist(a[j], x[i]));
        ans = max(ans, minDist);
    }
    cerr << ans << endl;
    cout << setprecision(6) << fixed << sqrt(ans) << endl;
}

bool ok(long long lim) {
    for (int i = 1; i <= n; ++i) cnt[i] = 0;
    for (int i = 1; i <= m; ++i) {
        int first = 1, last = n;
        if (cut[i] < n && dist(a[i], x[cut[i] + 1]) <= lim) first = cut[i] + 1;
        if (0 < cut[i] && dist(a[i], x[cut[i]]) <= lim) last = cut[i];
        int l = 1, r = cut[i];
        while (l <= r) {
            int mid = l + r >> 1;
            if (dist(a[i], x[mid]) <= lim) {
                first = mid;
                r = mid - 1;
            } else {
                l = mid + 1;
            }
        }
        l = cut[i] + (cut[i] == 0 || a[i].X != x[cut[i]]), r = n;
        while (l <= r) {
            int mid = l + r >> 1;
            if (dist(a[i], x[mid]) <= lim) {
                last = mid;
                l = mid + 1;
            } else {
                r = mid - 1;
            }
        }
        int L = dist(a[i], x[first]);
        int R = dist(a[i], x[last]);
        if (L > lim && R > lim) continue;
        if (L <= lim && R > lim) last = first;
        if (R <= lim && L > lim) first = last;
        /*
        for (int j = 1; j <= n; ++j)
            if (dist(a[i], x[j]) <= lim) cout << "ok " << i << ' ' << j << endl;
        cerr << lim << ' ' << i << ' ' << first << ' ' << last << endl;
        */
        if (max(dist(a[i], x[first]), dist(a[i], x[last])) <= lim) {
            //cerr << lim << ' ' << i << ' ' << first << ' ' << last << endl;
            ++cnt[first], --cnt[last + 1];
        }
    }
    for (int i = 1, now = 0; i <= n; ++i) {
        now += cnt[i];
        if (now <= 0) return 0;
    }
    return 1;
}

void initialize() {
    sort(x + 1, x + 1 + n);
    n = unique(x + 1, x + 1 + n) - x - 1;
    //for (int i = 1; i <= n; ++i) cout << x[i] << ' '; cout << endl;
    for (int i = 1; i <= m; ++i) {
        cut[i] = lower_bound(x + 1, x + 1 + n, a[i].X) - x;
        if (cut[i] <= n && x[cut[i]] > a[i].X) --cut[i];
        //cerr << "(" << a[i].X << ' ' << a[i].Y << ") " << cut[i] << ' ' << x[cut[i]] << endl;
    }
}

void solve() {
    long long ans = 0;
    long long l = 0, r = INF;
    while (l <= r) {
        long long mid = l + r >> 1;
        if (ok(mid)) {
            ans = mid;
            r = mid - 1;
        } else {
            l = mid + 1;
        }
    }
    //cerr << ans << endl;
    cout << setprecision(6) << fixed << sqrt(ans) << endl;
}

int main() {
    ios::sync_with_stdio(0); cin.tie(0);
#ifndef ONLINE_JUDGE
    genTest();
    freopen("KTOUR.txt", "r", stdin);
#endif
    cin >> n >> Y0;
    for (int i = 1; i <= n; ++i) cin >> x[i];
    cin >> m;
    for (int i = 1; i <= m; ++i) cin >> a[i].X >> a[i].Y;
    //naive();
    initialize();
    solve();
    return 0;
}

Code mẫu của RR

#include <sstream>
#include <iomanip>
#include <iostream>
#include <cstdio>
#include <cstring>
#include <cstdlib>
#include <cmath>
#include <algorithm>
#include <vector>
#include <set>
#include <map>
#include <stack>
#include <queue>
#include <string>
#include <deque>
#include <complex>

#define FOR(i,a,b) for(int i=(a),_b=(b); i<=_b; i++)
#define FORD(i,a,b) for(int i=(a),_b=(b); i>=_b; i--)
#define REP(i,a) for(int i=0,_a=(a); i<_a; i++)
using namespace std;

const int MN = 100111;

int n, m;
double delta;
int x[MN], a[MN], b[MN];
pair<double,double> range[MN];

#define sqr(x) ((x)*(x))

bool check(double r) {
    int top = 0;
    FOR(i,1,m) {
        double t = r*r - sqr(b[i] - delta);
        if (t >= 0) {
            t = sqrt(t);
            range[++top] = make_pair(a[i] - t, a[i] + t);
        }
    }
    sort(range+1, range+top+1);
    int j = 1;
    FOR(i,1,n) {
        while (j <= top && (x[i] > range[j].second || x[i] < range[j].first)) ++j;
        if (j == top+1) return false;
    }
    return true;
}

int main() {
    ios :: sync_with_stdio(false);
    cin >> n >> delta;
    FOR(i,1,n) cin >> x[i];
    cin >> m;
    FOR(i,1,m) cin >> a[i] >> b[i];
    sort(x+1, x+n+1);
    double l = 0, r = 200000, res = -1;
    REP(turn,100) {
        double mid = (l + r) / 2.0;
        if (check(mid)) r = mid, res = mid;
        else l = mid;
    }
    cout << (fixed) << setprecision(6) << res << endl;
    return 0;
}

Code mẫu của hieult

#include <set>
#include <map>
#include <list>
#include <cmath>
#include <queue>
#include <stack>
#include <cstdio>
#include <string>
#include <vector>
#include <cstdlib>
#include <cstring>
#include <sstream>
#include <iomanip>
#include <iostream>
#include <algorithm>

#include <ctime>
#include <deque>
#include <bitset>
#include <cctype>
#include <utility>
#include <cassert>

using namespace std;

typedef long long ll;
typedef double ld;
typedef unsigned int ui;
typedef unsigned long long ull;

#define Rep(i,n) for(int i = 0; i < (n); ++i)
#define Repd(i,n) for(int i = (n)-1; i >= 0; --i)
#define For(i,a,b) for(int i = (a); i <= (b); ++i)
#define Ford(i,a,b) for(int i = (a); i >= (b); --i)
//#define Fit(i,v) for(__typeof((v).begin()) i = (v).begin(); i != (v).end(); ++i)
//#define Fitd(i,v) for(__typeof((v).rbegin()) i = (v).rbegin(); i != (v).rend(); ++i)
#define mp make_pair
#define pb push_back
#define fi first
#define se second
#define sz(a) ((int)(a).size())
#define all(a) (a).begin(), (a).end()
#define ms(a,x) memset(a, x, sizeof(a))

template<class F, class T> T convert(F a, int p = -1) { stringstream ss; if (p >= 0) ss << fixed << setprecision(p); ss << a; T r; ss >> r; return r; }
template<class T> T gcd(T a, T b) { T r; while (b != 0) { r = a % b; a = b; b = r; } return a; }
template<class T> T lcm(T a, T b) { return a / gcd(a, b) * b; }
template<class T> T sqr(T x) { return x * x; }
template<class T> T cube(T x) { return x * x * x; }
template<class T> int getbit(T s, int i) { return (s >> i) & 1; }
template<class T> T onbit(T s, int i) { return s | (T(1) << i); }
template<class T> T offbit(T s, int i) { return s & (~(T(1) << i)); }
template<class T> int cntbit(T s) { return s == 0 ? 0 : cntbit(s >> 1) + (s & 1); }

const int bfsz = 1 << 16;
char bf[bfsz + 5];
int rsz = 0;
int ptr = 0;
char gc() {
    if (rsz <= 0) {
        ptr = 0;
        rsz = (int) fread(bf, 1, bfsz, stdin);
        if (rsz <= 0)
            return EOF;
    }
    --rsz;
    return bf[ptr++];
}
void ga(char &c) {
    c = EOF;
    while (!isalpha(c))
        c = gc();
}
int gs(char s[]) {
    int l = 0;
    char c = gc();
    while (isspace(c))
        c = gc();
    while (c != EOF && !isspace(c)) {
        s[l++] = c;
        c = gc();
    }
    s[l] = '\0';
    return l;
}
template<class T> bool gi(T &v) {
    v = 0;
    char c = gc();
    while (c != EOF && c != '-' && !isdigit(c))
        c = gc();
    if (c == EOF)
        return false;
    bool neg = c == '-';
    if (neg)
        c = gc();
    while (isdigit(c)) {
        v = v * 10 + c - '0';
        c = gc();
    }
    if (neg)
        v = -v;
    return true;
}

typedef pair<int, int> II;

const ld PI = acos(-1.0);
const ld eps = 1e-9;

const int dr[] = {0, +1, 0, -1};
const int dc[] = {+1, 0, -1, 0};

const int inf = (int)1e9 + 5;
const ll linf = (ll)1e16 + 5;
const ll mod = (ll)1e9 + 7;

#define maxn 100005

int n, m;
int x, y, X[maxn], Y[maxn], f[maxn];
vector<int> V;

bool thoaman(ld d){
    ms(f, 0);
    int u, l, r;
    For(i, 1, m){
        if(abs(Y[i] - y) > d) continue;
        u = (int)(sqrt(d * d - (Y[i] - y) * (Y[i] - y) + eps));
        l = lower_bound(all(V), X[i] - u) - V.begin();
        r = upper_bound(all(V), X[i] + u) - V.begin();
        f[l]++; f[r]--;
    }

    int run = 0;
    For(i, 1, n){
        run += f[i];
        if(run <= 0) return false;
    }
    return true;
}

int  main()
{
//  freopen("in.txt", "r", stdin);
    cin >> n >> y;
    For(i, 1, n) {
        scanf("%d", &x);
        V.pb(x);
    }
    cin >> m;
    For(i, 1, m) scanf("%d %d", &X[i], &Y[i]);
    V.pb(-inf); V.pb(inf);
    sort(all(V));

    ld l = 0, r = 1000000, mid;
    while(l < r - 0.00000001){
        mid = (l + r) / 2;
        if(thoaman(mid)) r = mid;
        else l = mid;
    }

    cout << fixed << setprecision(6) << l;
}

Code mẫu của ll931110

#include <algorithm>
#include <bitset>
#include <cmath>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <ctime>
#include <deque>
#include <fstream>
#include <functional>
#include <iostream>
#include <map>
#include <queue>
#include <set>
#include <sstream>
#include <stack>
#include <string>
#include <utility>
#include <vector>
#define point pair<long long,long long>
#define maxn 100005
using namespace std;

int m,n,Y;
int xcord[maxn];
vector< point > polygon;

long long crossProduct(point A,point B,point C)
{
    long long ax = B.first - A.first,ay = B.second - A.second;
    long long bx = C.first - B.first,by = C.second - B.second;
    return ax * by - ay * bx;
}

vector< point > upperHull(vector< point > polygon)
{
    vector< point > tmp = polygon;
    sort(tmp.begin(),tmp.end());
    polygon.clear();
    for (int i = 0; i < tmp.size(); i++)
      if (!i || tmp[i].first > tmp[i - 1].first) polygon.push_back(tmp[i]);

    if (polygon.size() < 2) return polygon;

    point p1 = polygon[0],p2 = polygon[polygon.size() - 1];
    vector< point > upper;
    upper.push_back(p1);

    for (int i = 1; i < polygon.size(); i++)
      if (i == polygon.size() - 1 || crossProduct(p1,polygon[i],p2) > 0)
      {
          while (upper.size() > 1 && crossProduct(upper[upper.size() - 2],upper[upper.size() - 1],polygon[i]) <= 0) upper.pop_back();
          upper.push_back(polygon[i]);
      }
    return upper;
}

long long query(int x)
{
    long long ans = 1LL << 60;
    int low = 0,high = polygon.size() - 1;
    while (high - low > 3)
    {
        int m1 = (low + low + high)/3,m2 = (low + high + high)/3;
        long long T1 = 1LL * polygon[m1].first * x + polygon[m1].second;
        long long T2 = 1LL * polygon[m2].first * x + polygon[m2].second;
        if (T1 < T2)
        {
            ans = min(ans,T1);  high = m2 - 1;
        }
        else
        {
            ans = min(ans,T2);  low = m1 + 1;
        }
    }
    for (int i = low; i <= high; i++) ans = min(ans,1LL * polygon[i].first * x + polygon[i].second);
    return 1LL * x * x + ans;
}

int main()
{
    scanf("%d %d", &m, &Y);
    for (int i = 0; i < m; i++) scanf("%d", &xcord[i]);

    scanf("%d", &n);
    for (int i = 0; i < n; i++)
    {
        int xk,yk;
        scanf("%d %d", &xk, &yk);
        point P;
        P.first = -2LL * xk;
        P.second = 1LL * xk * xk + 1LL * (Y - yk) * (Y - yk);
        polygon.push_back(P);
    }
    polygon = upperHull(polygon);

    long long ret = 0;
    for (int i = 0; i < m; i++) ret = max(ret,query(xcord[i]));
    double ans = sqrt(1.0 * ret);
    printf("%.6lf\n", ans);
}