제출 #642050

#	제출 시각	아이디	문제	언어	결과	실행 시간	메모리
642050		piOOE	Simurgh (IOI17_simurgh)	C++17	0 / 100	1 ms	340 KiB

simurgh

#include <bits/stdc++.h>
#include "simurgh.h"

using namespace std;

void my_assert(bool f) {
    if (!f) {
        cerr << "228\n";
        int x = 1337;
        while (!f) {
            x *= 2;
            cerr << "yay";
        }
    }
}

struct dsu {
    vector<int> p;

    dsu(int n = 0) {
        p.resize(n);
        iota(p.begin(), p.end(), 0);
    }

    int get(int x) {
        while (x != p[x]) x = p[x] = p[p[x]];
        return x;
    }

    bool same(int x, int y) {
        return get(x) == get(y);
    }

    bool unite(int x, int y) {
        x = get(x), y = get(y);
        if (x == y) {
            return false;
        }
        p[y] = x;
        return true;
    }
};


vector<int> find_roads(int n, std::vector<int> U, std::vector<int> V) {
    if (U.size() != n * (n - 1) / 2) {
        vector<pair<int, int>> par(n);
        vector<int> tin(n), tout(n);
        int T = 0, ans_st = 0;

        auto calc = [&](vector<int> st) {
            T = 0;
            ans_st = count_common_roads(st);
            vector<vector<pair<int, int>>> g(n);
            for (int i = 0; i < n - 1; ++i) {
                g[U[st[i]]].emplace_back(V[st[i]], i);
                g[V[st[i]]].emplace_back(U[st[i]], i);
            }
            function<void(int)> dfs = [&](int v) {
                tin[v] = T++;
                for (auto [to, i]: g[v]) {
                    if (to != par[v].first) {
                        par[to] = {v, i};
                        dfs(to);
                    }
                }
                tout[v] = T;
            };
            dfs(0);
        };

        int m = U.size();

        dsu d(n);
        vector<int> st;
        vector<bool> in_st(m);
        for (int i = 0; i < m; ++i) {
            in_st[i] = d.unite(U[i], V[i]);
            if (in_st[i]) {
                st.push_back(i);
            }
        }


        auto isp = [&](int x, int y) {
            return tin[x] <= tin[y] && tout[x] >= tout[y];
        };

        auto path = [&](int x, int y) -> vector<int> {
            int y_ = y, x_ = x;
            vector<int> ans;
            while (!isp(x, y_)) {
                ans.push_back(par[x].second);
                x = par[x].first;
            }
            while (!isp(y, x_)) {
                ans.push_back(par[y].second);
                y = par[y].first;
            }
            return ans;
        };

        calc(st);

        vector<bool> sure(m);

        for (int i = 0; i < m; ++i) {
            if (find(st.begin(), st.end(), i) == st.end()) {
                vector<int> now = path(U[i], V[i]);
                vector<int> vis;
                bool yay = false;
                for (int j: now) {
                    if (!sure[st[j]]) {
                        auto q = st;
                        q.erase(q.begin() + j);
                        q.push_back(i);
                        int val = count_common_roads(q);
                        if (val > ans_st) {
                            st = q;
                            sure[i] = true;
                            calc(st);
                            yay = true;
                            break;
                        } else if (val < ans_st) {
                            sure[st[j]] = true;
                            break;
                        } else {
                            vis.push_back(st[j]);
                        }
                    }
                }
                if (yay) {
                    for (int j: vis) {
                        sure[j] = true;
                    }
                } else {
                    if (!vis.empty()) {
                        for (int j: vis) {
                            auto it = find(st.begin(), st.end(), j);
                            if (it != st.end()) {
                                st.erase(it);
                            }
                        }
                        dsu s(n);
                        for (int j: st) {
                            assert(s.unite(U[j], V[j]));
                        }
                        for (int j = i + 1; j < m; ++j) {
                            if (s.unite(U[j], V[j])) {
                                st.push_back(j);
                            }
                        }
                        calc(st);
                    }
                }
            }
        }
        return st;
    } else {
        vector a(n, vector<int>(n, -1)), id(n, vector<int>(n));
        const int m = n * (n - 1) / 2;
        for (int i = 0; i < m; ++i) {
            id[U[i]][V[i]] = id[V[i]][U[i]] = i;
        }
        vector<int> cnt(n), left(n);
        for (int i = 0; i < n; ++i) {
            vector<int> q;
            for (int j = 0; j < n; ++j) {
                if (j != i) {
                    q.push_back(id[i][j]);
                }
            }
            cnt[i] = count_common_roads(q);
        }
        vector<int> ans;
        vector<bool> used(n);
        for (int iter = 0; iter < n; ++iter) {
            int v = -1;
            for (int i = 0; i < n; ++i) {
                if (!used[i] && (v == -1 || left[v] > left[i])) {
                    v = i;
                }
            }
            used[v] = true;
            int chosen = -1;
            if (left[v] != 0) {
                assert(left[v] == 1);
                vector<int> c;
                for (int to = 0; to < n; ++to) {
                    if (to != v && a[v][to] == -1) {
                        c.push_back(id[v][to]);
                    }
                }
                while (c.size() != 1) {
                    int wait = c.size() & 1 ? c.back() : -1;
                    if (c.size() & 1) {
                        c.pop_back();
                    }
                    int sz = c.size() >> 1;
                    vector<int> st;
                    vector<bool> in_c(n);
                    for (int x: c) {
                        in_c[x] = true;
                    }
                    for (int to = 0; to < n; ++to) {
                        if (to != v && !in_c[to]) {
                            st.push_back(id[v][to]);
                        }
                    }
                    for (int i = 0; i < sz; ++i) {
                        st.push_back(id[c[i]][c[i + sz]]);
                    }
                    vector<int> L(st);
                    for (int i = 0; i < sz; ++i) {
                        L.push_back(id[v][c[i]]);
                    }
                    vector<int> R(st);
                    for (int i = sz; i < sz * 2; ++i) {
                        R.push_back(id[v][c[i]]);
                    }
                    int cntL = count_common_roads(L), cntR = count_common_roads(R);
                    if (cntL == cntR) {
                        assert(wait != -1);
                        c.clear();
                    } else if (cntL < cntR) {
                        c.erase(c.begin(), c.begin() + sz);
                    } else {
                        c.resize(sz);
                    }
                    if (wait != -1) {
                        c.push_back(wait);
                    }
                }
                assert(!c.empty());
                chosen = c[0];
                ans.push_back(id[v][chosen]);
            }
            for (int to = 0; to < n; ++to) {
                if (to != v && a[v][to] == -1) {
                    if (to != chosen) {
                        a[v][to] = a[to][v] = 0;
                    } else {
                        a[v][to] = a[to][v] = 1;
                    }
                }
            }
        }
    }
}

컴파일 시 표준 에러 (stderr) 메시지

simurgh.cpp: In function 'std::vector<int> find_roads(int, std::vector<int>, std::vector<int>)':
simurgh.cpp:46:18: warning: comparison of integer expressions of different signedness: 'std::vector<int>::size_type' {aka 'long unsigned int'} and 'int' [-Wsign-compare]
   46 |     if (U.size() != n * (n - 1) / 2) {
      |         ~~~~~~~~~^~~~~~~~~~~~~~~~~~
simurgh.cpp:249:1: warning: control reaches end of non-void function [-Wreturn-type]
  249 | }
      | ^

• Subtask 1: 0 / 13
• Subtask 2: 0 / 17
• Subtask 3: 0 / 21
• Subtask 4: 0 / 19
• Subtask 5: 0 / 30