verify/library_checker/tree/cartesian_tree.test.cpp

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Last update: 2024-11-09 01:34:39+09:00
Problem: https://judge.yosupo.jp/problem/cartesian_tree

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Code

#define PROBLEM "https://judge.yosupo.jp/problem/cartesian_tree"
#include "../../../src/template/template.hpp"
#include "../../../src/tree/cartesian_tree.hpp"
int main(void) {
    int n;
    cin >> n;
    vector<int> a(n);
    rep(i, 0, n) cin >> a[i];
    auto [tree, root] = cartesian_tree(a);
    vector<int> ans(n);
    ans[root] = root;
    rep(i, 0, n) {
        for(const int to : tree[i]) {
            ans[to] = i;
        }
    }
    rep(i, 0, n) {
        cout << ans[i] << " \n"[i + 1 == n];
    }
}

#line 1 "verify/library_checker/tree/cartesian_tree.test.cpp"
#define PROBLEM "https://judge.yosupo.jp/problem/cartesian_tree"
#line 2 "src/template/template.hpp"
#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using P = pair<long long, long long>;
#define rep(i, a, b) for(long long i = (a); i < (b); ++i)
#define rrep(i, a, b) for(long long i = (a); i >= (b); --i)
constexpr long long inf = 4e18;
struct SetupIO {
    SetupIO() {
        ios::sync_with_stdio(0);
        cin.tie(0);
        cout << fixed << setprecision(30);
    }
} setup_io;
#line 3 "src/graph/graph_template.hpp"
template <typename T>
struct Edge {
    int from, to;
    T cost;
    int idx;
    Edge()
        : from(-1), to(-1), cost(-1), idx(-1) {}
    Edge(const int from, const int to, const T& cost = 1, const int idx = -1)
        : from(from), to(to), cost(cost), idx(idx) {}
    operator int() const {
        return to;
    }
};
template <typename T>
struct Graph {
    Graph(const int N)
        : n(N), es(0), g(N) {}
    int size() const {
        return n;
    }
    int edge_size() const {
        return es;
    }
    void add_edge(const int from, const int to, const T& cost = 1) {
        assert(0 <= from and from < n);
        assert(0 <= to and to < n);
        g[from].emplace_back(from, to, cost, es);
        g[to].emplace_back(to, from, cost, es++);
    }
    void add_directed_edge(const int from, const int to, const T& cost = 1) {
        assert(0 <= from and from < n);
        assert(0 <= to and to < n);
        g[from].emplace_back(from, to, cost, es++);
    }
    inline vector<Edge<T>>& operator[](const int& k) {
        assert(0 <= k and k < n);
        return g[k];
    }
    inline const vector<Edge<T>>& operator[](const int& k) const {
        assert(0 <= k and k < n);
        return g[k];
    }

   private:
    int n, es;
    vector<vector<Edge<T>>> g;
};
template <typename T>
using Edges = vector<Edge<T>>;
#line 4 "src/tree/cartesian_tree.hpp"
template <typename T>
pair<Graph<int>, int> cartesian_tree(const vector<T>& a) {
    const int n = (int)a.size();
    Graph<int> g(n);
    vector<int> p(n, -1), st;
    st.reserve(n);
    for(int i = 0; i < n; ++i) {
        int prv = -1;
        while(!st.empty() and a[i] < a[st.back()]) {
            prv = st.back();
            st.pop_back();
        }
        if(prv != -1) p[prv] = i;
        if(!st.empty()) p[i] = st.back();
        st.emplace_back(i);
    }
    int root = -1;
    for(int i = 0; i < n; ++i) {
        if(p[i] != -1) g.add_directed_edge(p[i], i);
        else root = i;
    }
    return {g, root};
}
#line 4 "verify/library_checker/tree/cartesian_tree.test.cpp"
int main(void) {
    int n;
    cin >> n;
    vector<int> a(n);
    rep(i, 0, n) cin >> a[i];
    auto [tree, root] = cartesian_tree(a);
    vector<int> ans(n);
    ans[root] = root;
    rep(i, 0, n) {
        for(const int to : tree[i]) {
            ans[to] = i;
        }
    }
    rep(i, 0, n) {
        cout << ans[i] << " \n"[i + 1 == n];
    }
}