Submission #715263

#	Time	Username	Problem	Language	Result	Execution time	Memory
715263		Stickfish	Evacuation plan (IZhO18_plan)	C++17	100 / 100	1342 ms	47212 KiB

plan

#include <iostream>
#include <vector>
#include <algorithm>
#include <set>
using namespace std;

struct dsu {
    void resize(int n) {
        rt.resize(n);
        sz.assign(n, 1);
        for (int i = 0; i < n; ++i)
            rt[i] = {i, 0};
    }

    int gst(int i) {
        if (rt[i].first == i)
            return i;
        return gst(rt[i].first);
    }

    int gstwr(int i, int mxw) {
        if (rt[i].first == i || rt[i].second > mxw)
            return i;
        return gstwr(rt[i].first, mxw);
    }

    void unite(int i, int j, int w) {
        i = gst(i);
        j = gst(j);
        if (i == j)
            return;
        if (sz[i] < sz[j])
            swap(i, j);
        sz[i] += sz[j];
        rt[j] = {i, w};
    }
 private:
     vector<pair<int, int>> rt;
     vector<int> sz;
};

const int MAXN = 1e5 + 123;
const int INF = 1e9 + 177013;
vector<pair<int, int>> edgw[MAXN];
vector<int> edg[MAXN];
int depth[MAXN];

void get_depth(int n) {
    int k;
    cin >> k;
    vector<int> sts(k);
    for (int i = 0; i < k; ++i)
        cin >> sts[i], --sts[i];
    set<pair<int, int>> rdepth;
    for (int i = 0; i < n; ++i)
        depth[i] = INF;
    for (auto i : sts) {
        depth[i] = 0;
        rdepth.insert({depth[i], i});
    }
    while (rdepth.size()) {
        auto [d, v] = *rdepth.begin();
        rdepth.erase(rdepth.begin());
        if (depth[v] < d)
            continue;
        for (auto [u, w] : edgw[v]) {
            if (depth[u] > d + w) {
                depth[u] = d + w;
                rdepth.insert({depth[u], u});
            }
        }
    }
}

signed main() {
    int n, m;
    cin >> n >> m;
    for (int t = 0; t < m; ++t) {
        int u, v, w;
        cin >> u >> v >> w;
        --u, --v;
        edgw[u].push_back({v, w});
        edgw[v].push_back({u, w});
        edg[u].push_back(v);
        edg[v].push_back(u);
    }
    get_depth(n);
    //for (int i = 0; i < n; ++i)
        //cout << depth[i] << ' ';
    //cout << endl;
    vector<pair<int, pair<int, int>>> edges;
    for (int v = 0; v < n; ++v) for (auto u : edg[v]) {
        if (u > v)
            edges.push_back({min(depth[v], depth[u]), {v, u}});
    }
    sort(edges.rbegin(), edges.rend());
    dsu su;
    su.resize(n);
    for (int i = 0; i < m; ++i) {
        su.unite(edges[i].second.first, edges[i].second.second, i);
    }
    int q;
    cin >> q;
    while (q--) {
        int s, t;
        cin >> s >> t;
        --s, --t;
        int lb = -1, ub = m;
        while (ub - lb > 1) {
            int mb = (lb + ub) / 2;
            if (su.gstwr(s, mb) == su.gstwr(t, mb))
                ub = mb;
            else
                lb = mb;
        }
        cout << min({edges[ub].first, depth[s], depth[t]}) << '\n';
    }
}

• Subtask 1: 10 / 10
• Subtask 2: 13 / 13
• Subtask 3: 12 / 12
• Subtask 4: 19 / 19
• Subtask 5: 46 / 46