Submission #169290

#	Time	Username	Problem	Language	Result	Execution time	Memory
169290		blast	Evacuation plan (IZhO18_plan)	C++14	100 / 100	1364 ms	99152 KiB

plan

#include <bits/stdc++.h>

//#define FILENAME ""

#define all(a) (a).begin(), (a).end()
#define sz(a) (int)(a).size()
#define pb push_back

#define F first
#define S second

using namespace std;

#define int long long

const int N = 1e5 + 5;
const int INF = 1e12 + 5;
const double PI = acos(-1);

typedef long long ll;

const int dx[] = {1, -1, 0, 0};
const int dy[] = {0, 0, 1, -1};

const int mod = 1e9 + 7;

int n, m, k, d[N], up[21][N], cost[21][N], p[N], s[N], h[N];
vector<pair<int,int>> g[N];
vector<int> gr[N];

int get(int a) {
    if (p[a] == a) return a;
    return p[a] = get(p[a]);
}

void unite(int a, int b) {
    if (s[a] < s[b]) swap(a, b);
    s[a] += s[b];
    p[b] = a;
}

void dfs(int v, int p = 0) {
    h[v] = h[p] + 1;
    up[0][v] = p;
    cost[0][v] = min(d[v], d[p]);
    for (int i = 1; i <= 20; i++) {
        up[i][v] = up[i - 1][up[i - 1][v]];
        cost[i][v] = min(cost[i - 1][v], cost[i - 1][up[i - 1][v]]);
    }
    for (int i = 0; i < sz(gr[v]); i++) {
        int to = gr[v][i];
        if (to != p) dfs(to, v);
    }
}

int ans(int a, int b) {
    int mn = INF;
    if (h[a] > h[b]) {
        swap(a, b);
    }
    for (int i = 20; i >= 0; i--) {
        if (h[a] <= h[up[i][b]]) {
            mn = min(mn, cost[i][b]);
            b = up[i][b];
        }
    }
    if (a == b) return mn;
    for (int i = 20; i >= 0; i--) {
        if (up[i][a] != up[i][b]) {
            mn = min(mn, cost[i][a]);
            mn = min(mn, cost[i][b]);
            b = up[i][b];
            a = up[i][a];
        }
    }
    return min({mn, cost[0][a], cost[0][b]});
}

main() {
    #ifdef FILENAME
        freopen(FILENAME".in", "r", stdin);
        freopen(FILENAME ".out", "w", stdout);
    #endif
    ios_base::sync_with_stdio(0);
    cin.tie(0);
    cin >> n >> m;
    for (int i = 1, u, v, x; i <= m; i++) {
        cin >> u >> v >> x;
        g[u].pb({v, x});
        g[v].pb({u, x});
    }
    set<pair<int,int>> st;
    for (int i = 0; i <= n; i++) {
        d[i] = INF;
    }
    cin >> k;
    for (int i = 1, x; i <= k; i++) {
        cin >> x;
        d[x] = 0;
        st.insert({0, x});
    }
    while(st.size()) {
        int v = st.begin() -> second;
        st.erase(st.begin());
        for (int i = 0; i < sz(g[v]); i++) {
            int to = g[v][i].F;
            int len = g[v][i].S;
            if (d[v] + len < d[to]) {
                st.erase({d[to], to});
                d[to] = d[v] + len;
                st.insert({d[to], to});
            }
        }
    }
    vector<pair<int,pair<int,int>>> w;
    for (int i = 1; i <= n; i++) {
        p[i] = i;
        s[i] = 1;
        for (int j = 0; j < sz(g[i]); j++) {
            w.pb({min(d[i], d[g[i][j].F]), {i, g[i][j].F}});
        }
    }
    sort(all(w));
    for (int i = sz(w) - 1; i >= 0; i--) {
        int a = w[i].S.F, b = w[i].S.S;
        if (get(a) != get(b)) {
            unite(get(a), get(b));
            gr[a].pb(b);
            gr[b].pb(a);
        }
    }
    for (int i = 0; i <= 20; i++)
        for (int j = 1; j <= N - 5; j++)
            cost[i][j] = INF;
    dfs(1);
    int q;
    cin >> q;
    while(q--) {
        int a, b;
        cin >> a >> b;
        cout << ans(a, b) << "\n";
    }
    return 0;
}

Compilation message (stderr)

plan.cpp:79:6: warning: ISO C++ forbids declaration of 'main' with no type [-Wreturn-type]
 main() {
      ^

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