Language: C++

#include <bits/stdc++.h>
using namespace std;

// template {{{
#define pb push_back
#define eb emplace_back
#define mp make_pair
#define mt make_tuple
#define lb lower_bound
#define ub upper_bound
#define f first
#define s second
#define resz resize

#define sz(x) int((x).size())
#define all(x) (x).begin(), (x).end()

#define FOR(i, a, b) for (int i = (a); i < (b); i++)
#define F0R(i, a) for (int i = 0; i < (a); i++)
#define FORd(i, a, b) for (int i = (b)-1; i >= (a); i--)
#define F0Rd(i, a) for (int i = (a)-1; i >= 0; i--)
#define trav(a, x) for (auto& a : x)

#define sort_by(x, y) sort(all(x), [&](const auto& a, const auto& b) { return y; })

using ll = long long;
using vi = vector<int>;
using vvi = vector<vi>;
using vll = vector<ll>;
using vvll = vector<vll>;
using vb = vector<bool>;
using vd = vector<double>;
using vs = vector<string>;

using pii = pair<int, int>;
using pll = pair<ll, ll>;
using pdd = pair<double, double>;

using vpii = vector<pii>;
using vvpii = vector<vpii>;
using vpll = vector<pll>;
using vvpll = vector<vpll>;
using vpdd = vector<pdd>;
using vvpdd = vector<vpdd>;

template<typename T> void ckmin(T& a, const T& b) { a = min(a, b); }
template<typename T> void ckmax(T& a, const T& b) { a = max(a, b); }

mt19937_64 rng(chrono::steady_clock::now().time_since_epoch().count());

namespace __input {
    template<class T1, class T2> void re(pair<T1,T2>& p);
    template<class T> void re(vector<T>& a);
    template<class T, size_t SZ> void re(array<T,SZ>& a);

    template<class T> void re(T& x) { cin >> x; }
    void re(double& x) { string t; re(t); x = stod(t); }
    template<class Arg, class... Args> void re(Arg& first, Args&... rest) {
        re(first); re(rest...);
    }

    template<class T1, class T2> void re(pair<T1,T2>& p) { re(p.f,p.s); }
    template<class T> void re(vector<T>& a) { F0R(i,sz(a)) re(a[i]); }
    template<class T, size_t SZ> void re(array<T,SZ>& a) { F0R(i,SZ) re(a[i]); }
}
using namespace __input;

namespace __output {
    template<class T1, class T2> void pr(const pair<T1,T2>& x);
    template<class T, size_t SZ> void pr(const array<T,SZ>& x);
    template<class T> void pr(const vector<T>& x);
    template<class T> void pr(const set<T>& x);
    template<class T1, class T2> void pr(const map<T1,T2>& x);

    template<class T> void pr(const T& x) { cout << x; }
    template<class Arg, class... Args> void pr(const Arg& first, const Args&... rest) {
        pr(first); pr(rest...);
    }

    template<class T1, class T2> void pr(const pair<T1,T2>& x) {
        pr("{",x.f,", ",x.s,"}");
    }
    template<class T, bool pretty = true> void prContain(const T& x) {
        if (pretty) pr("{");
        bool fst = 1; for (const auto& a: x) pr(!fst?pretty?", ":" ":"",a), fst = 0;
        if (pretty) pr("}");
    }
    template<class T> void pc(const T& x) { prContain<T, false>(x); pr("\n"); }
    template<class T, size_t SZ> void pr(const array<T,SZ>& x) { prContain(x); }
    template<class T> void pr(const vector<T>& x) { prContain(x); }
    template<class T> void pr(const set<T>& x) { prContain(x); }
    template<class T1, class T2> void pr(const map<T1,T2>& x) { prContain(x); }

    void ps() { pr("\n"); }
    template<class Arg> void ps(const Arg& first) {
        pr(first); ps();
    }
    template<class Arg, class... Args> void ps(const Arg& first, const Args&... rest) {
        pr(first," "); ps(rest...);
    }
}
using namespace __output;

#define TRACE(x) x
#define __pn(x) pr(#x, " = ")
#define pd(...) __pn((__VA_ARGS__)), ps(__VA_ARGS__), cout << flush

namespace __algorithm {
    template<typename T> void dedup(vector<T>& v) {
        sort(all(v)); v.erase(unique(all(v)), v.end());
    }
    template<typename T> typename vector<T>::iterator find(vector<T>& v, const T& x) {
        auto it = lower_bound(all(v), x); return it != v.end() && *it == x ? it : v.end();
    }
    template<typename T> size_t index(vector<T>& v, const T& x) {
        auto it = find(v, x); assert(it != v.end() && *it == x); return it - v.begin();
    }

    template<typename C, typename T> vector<T> prefixes(const C& v, T zero) {
        vector<T> res(sz(v) + 1, zero); F0R (i, sz(v)) res[i+1] = res[i] + v[i]; return res;
    }
    template<typename C, typename T> vector<T> suffixes(const C& v, T zero) {
        vector<T> res(sz(v) + 1, zero); F0Rd (i, sz(v)) res[i] = v[i] + res[i+1]; return res;
    }
}
using namespace __algorithm;

struct monostate {
    friend istream& operator>>(istream& is, const __attribute__((unused))monostate& ms) { return is; }
    friend ostream& operator<<(ostream& os, const __attribute__((unused))monostate& ms) { return os; }
} ms;

template<typename W=monostate> struct wedge {
    int u, v, i; W w;
    wedge<W>(int _u=-1, int _v=-1, int _i=-1) : u(_u), v(_v), i(_i) {}
    int operator[](int loc) const { return u ^ v ^ loc; }
    friend void re(wedge& e) { re(e.u, e.v, e.w); --e.u, --e.v; }
    friend void pr(const wedge& e) { pr(e.u, "<-", e.w, "->", e.v); }
};

namespace __io {
    void setIn(string s) { freopen(s.c_str(),"r",stdin); }
    void setOut(string s) { freopen(s.c_str(),"w",stdout); }
    void setIO(string s = "") {
        ios_base::sync_with_stdio(0); cin.tie(0); cout.precision(15);
        if (sz(s)) { setIn(s+".in"), setOut(s+".out"); }
    }
}
using namespace __io;
// }}}

tuple<int, vi> strongly_connected_components(const vvi& graph) {
    const int N = graph.size();
    int C = 0, V = 0, top = 0;
    vi comp(N, -1), inx(N, -1), stack(N + 1, -1);

    auto tarjan = [&](auto&& self, int loc) -> int {
        stack[top++] = loc;
        int low = inx[loc] = V++;
        for (int nbr : graph[loc]) {
            if (inx[nbr] == -1) low = min(low, self(self, nbr));
            else if (comp[nbr] == -1) low = min(low, inx[nbr]);
        }
        if (low == inx[loc]) {
            while (stack[top] != loc)
                comp[stack[--top]] = C;
            C++;
        }
        return low;
    };

    for (int i = 0; i < N; i++) {
        if (inx[i] == -1)
            tarjan(tarjan, i);
    }
    return { C, comp };
}

int main() {
    setIO();

    int N; re(N); vpii locs(N); re(locs);

    vpii neg;
    F0R (i, N) {
        neg.eb(locs[i].f, 2 * i);
        neg.eb(locs[i].s, 2 * i + 1);
    }
    sort(all(neg));
    vi index(2 * N); F0R (i, 2 * N) index[neg[i].s] = i;

    int ans = 0, lo = 1, hi = 1e9;
    while (lo <= hi) {
        int mi = (lo + hi) / 2;

        vvi adj(4 * N);
        FOR (v, 1, 2 * N) {
            adj[v].pb(2 * v);
            adj[v].pb(2 * v + 1);
        }

        auto ins = [&](int i, int l, int r) {
            for (i += 2 * N, l += 2 * N, r += 2 * N; l < r; l /= 2, r /= 2) {
                if (l&1) adj[i].pb(l++);
                if (r&1) adj[i].pb(--r);
            }
        };

        F0R (f, 2 * N) {
            int l = neg[f].f;
            int i = lb(all(neg), mp(l - mi + 1, -1)) - neg.begin();
            int j = lb(all(neg), mp(l + mi, -1)) - neg.begin();
            ins(index[neg[f].s^1], i, f);
            ins(index[neg[f].s^1], f+1, j);
        }

        bool ok = true;
        vi scc = get<1>(strongly_connected_components(adj));
        F0R (f, N) ok &= scc[2 * N + index[2 * f]] != scc[2 * N + index[2 * f + 1]];

        if (ok) ans = mi, lo = mi + 1;
        else hi = mi - 1;
    }

    ps(ans);

    return 0;
}



Compiler output:
a.cc:133:21: error: reference to 'monostate' is ambiguous
  133 | template<typename W=monostate> struct wedge {
      |                     ^~~~~~~~~
In file included from /usr/include/x86_64-linux-gnu/c++/14/bits/stdc++.h:80,
                 from a.cc:1:
/usr/include/c++/14/variant:1237:10: note: candidates are: 'struct std::monostate'
 1237 |   struct monostate { };
      |          ^~~~~~~~~
a.cc:128:8: note:                 'struct monostate'
  128 | struct monostate {
      |        ^~~~~~~~~