Submission #169216

#	Time	Username	Problem	Language	Result	Execution time	Memory
169216		blast	Evacuation plan (IZhO18_plan)	C++14	0 / 100	180 ms	27528 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 = 1e9 + 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, u[N], v[N], d[N], p[N], s[N];
vector<pair<int,int>> g[N];
set<pair<int,int>> st;
vector<int> gr[N];
int tin[N], tout[N], timer, up[N][21], cost[N][21], h[N];

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

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

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

bool upper(int a, int b) {
    return tin[a] <= tin[b] && tout[a] >= tout[b];
}

int lca(int a, int b) {
    if (upper(a, b)) return a;
    if (upper(b, a)) return b;
    for (int i = 20; i >= 0; i--) {
        if (!upper(up[a][i], b) && up[a][i]) a = up[a][i];
    }
    return up[a][0];
}

int ans(int a, int res) {
    int mn = d[a];
    if (res == 0) return mn;
    for (int i = 0; i <= 20 && res; i++, res >>= 1) {
        if (res & 1) {
            mn = min(mn, cost[a][i]);
            a = up[a][i];
        }
    }
    return min(mn, cost[a][0]);
}

int 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, x; i <= m; i++) {
        cin >> u[i] >> v[i] >> x;
        g[u[i]].pb({v[i], x});
        g[v[i]].pb({u[i], x});
    }
    cin >> k;
    for (int i = 1; i <= n; i++) {
        d[i] = INF;
        p[i] = i;
        s[i] = 1;
    }
    for (int i = 1; i <= k; i++) {
        int x;
        cin >> x;
        st.insert({0, x});
        d[x] = 0;
    }
    while(st.size()) {
        int v = st.begin() -> S;
        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 <= m; i++) {
        w.pb({min(d[u[i]], d[v[i]]),{u[i], v[i]}});
    }
    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(a, b);
            gr[a].pb(b);
            gr[b].pb(a);
        }
    }
    d[0] = INF;
    for (int i = 1; i <= N - 5; i++)
        for (int j = 0; j <= 20; j++)
            cost[i][j] = INF;
    dfs(1, 0);
    int q;
    cin >> q;
    while(q--) {
        int a, b;
        cin >> a >> b;
        int l = lca(a, b);
        cout << min(ans(a, h[a] - h[l]), ans(b, h[b] - h[l])) << "\n";
    }
    return 0;
}

• Subtask 1: 0 / 10
• Subtask 2: 0 / 13
• Subtask 3: 0 / 12
• Subtask 4: 0 / 19
• Subtask 5: 0 / 46