Submission #1093991

#	Time	Username	Problem	Language	Result	Execution time	Memory
1093991		HNa_seawjing	Evacuation plan (IZhO18_plan)	C++14	100 / 100	373 ms	110324 KiB

plan

#include <bits/stdc++.h>
#define pb          emplace_back
#define ll          long long
#define fi          first
#define se          second
#define mp          make_pair
//#define int         int64_t
 
using namespace std;
 
const int N = int(5e5) + 7;
const int inf = 1e9 + 1;
typedef pair<ll, ll> pii;
 
int n, m, k, d[N], q, u, v, w;
vector<pii> adj[N];
 
struct TEdges {
    int u, v, w;
    TEdges() {u = v = w = 0;}
    TEdges(int u, int v, int w): u(u), v(v), w(w) {}
    bool operator < (const TEdges& x)const& {
        return w > x.w;
    }
};
vector<TEdges> edges;
priority_queue<pii, vector<pii>, greater<pii>> pq;
 
int lab[N];
int find(int x) {return lab[x] < 0? x: lab[x] = find(lab[x]);}
bool uni(int x, int y) {
    x = find(x), y = find(y);
    if(x == y) return 0;
    if(lab[x] > lab[y]) swap(x, y);
    lab[x] += lab[y], lab[y] = x;
    return 1;
}
 
const int logN = 20;
int p[N][logN + 1], mn[N][logN + 1], h[N];
void dfs(int u) {
    for(int i = 1; i <= logN; ++i) {
        p[u][i] = p[p[u][i - 1]][i - 1];
        mn[u][i] = min(mn[u][i - 1], mn[p[u][i - 1]][i - 1]);
    }
    for(auto& v: adj[u]) {
        if(v.fi == p[u][0]) continue;
        p[v.fi][0] = u;
        mn[v.fi][0] = v.se;
        h[v.fi] = h[u] + 1;
        dfs(v.fi);
    }
}
 
int get_min(int u, int v) {
    if(h[u] < h[v]) swap(u, v);
    int res = inf;
    for(int i = logN; i >= 0; --i) {
        if(h[u] - (1 << i) >= h[v]) {
            res = min(res, mn[u][i]);
            u = p[u][i];
        }
    }
    if(u == v) return res;
    for(int i = logN; i >= 0; --i) {
        if(p[u][i] != p[v][i]) {
            res = min({res, mn[u][i], mn[v][i]});
            u = p[u][i], v = p[v][i];
        }
    }
    res = min({res, mn[u][0], mn[v][0]});
    return res;
}
 
int32_t main() {
    ios_base::sync_with_stdio(0);
    cin.tie(0), cout.tie(0);
    #define Task        "test"
    if(fopen(Task".inp", "r")) {
        freopen(Task".inp", "r", stdin);
        freopen(Task".out", "w", stdout);
    }
    cin >> n >> m;
    for(int i = 1; i <= m; ++i) {
        cin >> u >> v >> w;
        adj[u].pb(v, w);
        adj[v].pb(u, w);
        edges.pb(u, v, w);
    }
    fill_n(&mn[0][0], N * (logN + 1), inf);
    fill(lab, lab + n + 1, -1);
    fill(d, d + n + 1, inf);
    cin >> k;
    for(int i = 1; i <= k; ++i) {
        cin >> u;
        d[u] = 0, pq.emplace(d[u], u);
    }
    pii top;
    while(pq.size()) {
        top = pq.top(); pq.pop();
        if(top.fi != d[top.se]) continue;
        for(auto& v: adj[top.se]) {
            if(top.fi + v.se < d[v.fi]) {
                d[v.fi] = top.fi + v.se;
                pq.emplace(d[v.fi], v.fi);
            }
        }
    }
    for(auto& e: edges) e.w = min(d[e.u], d[e.v]);
    sort(edges.begin(), edges.end());
    for(int i = 1; i <= n; ++i) adj[i].clear();
    for(auto &e: edges) {
        if(uni(e.u, e.v)) {
            adj[e.u].pb(e.v, e.w);
            adj[e.v].pb(e.u, e.w);
        }
    }
    dfs(1);
    cin >> q;
    while(q --) {
        cin >> u >> v;
        cout << get_min(u, v) << '\n';
    }
}

Compilation message (stderr)

plan.cpp: In function 'int32_t main()':
plan.cpp:80:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   80 |         freopen(Task".inp", "r", stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~
plan.cpp:81:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   81 |         freopen(Task".out", "w", stdout);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~

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