Submission #1162541

#	Time	Username	Problem	Language	Result	Execution time	Memory
1162541		CrabCNH	Cities (BOI16_cities)	C++20	0 / 100	261 ms	46676 KiB

cities

#include <bits/stdc++.h>

#define task   "BriantheCrab"

#define int    long long
#define pii    pair <int, int>
#define fi     first
#define se     second
#define szf    sizeof
#define sz(s)  (int)((s).size())

using namespace std;

template <class T> void mini (T &t, T f) {if (t > f) t = f;}
template <class T> void maxi (T &t, T f) {if (t < f) t = f;}

const int maxN = 2e5 + 5;
const int inf = 1e18 + 7;
const int mod = 1e9 + 7;

struct Edge {
    int u, w, s;
};

struct cmp {
    bool operator () (Edge A, Edge B) {
        return A.w > B.w;
    }
};

struct Path {
    int u, v, w;
};

int n, m, k;
int par[maxN], sz[maxN], curS[maxN];
map <pii, int> ck;
bool mp[maxN];
vector <int> spe;
vector <pii> adj[maxN];
vector <Path> all, nAll;
pii L[maxN]; // dis, source

bool cmpEdge (Path A, Path B) {
    return A.w < B.w;
}

void init () {
    for (int i = 1; i <= n; i ++) {
        par[i] = i;
        sz[i] = 1;
        curS[i] = mp[i];
    }
}

int getRoot (int u) {
    if (par[u] == u) {
        return u;
    }
    return (par[u] = getRoot (par[u]));
}

void merge (int u, int v) {
    u = getRoot (u);
    v = getRoot (v);
    if (u == v) {
        return;
    }
    if (sz[u] < sz[v]) {
        swap (u, v);
    }
    par[v] = u;
    sz[u] += sz[v];
    curS[u] += curS[v];
}

void multiSources () {
    priority_queue <Edge, vector <Edge>, cmp> pq;
    for (int i = 1; i <= n; i ++) {
        L[i] = {inf, -1};
    }
    for (auto u : spe) {
        L[u] = {0, u};
        pq.push ({u, L[u].fi, u});
    }
    while (!pq.empty ()) {
        auto [u, c, source] = pq.top ();
        pq.pop ();
        if (c > L[u].fi) {
            continue;
        }
        for (auto [v, dis] : adj[u]) {
            if (L[v].fi > L[u].fi + dis) {
                L[v] = {L[u].fi + dis, L[u].se};
                pq.push ({v, L[v].fi, L[v].se});
            }
        }
    }
}

void solve () {
    cin >> n >> k >> m;
    for (int i = 1; i <= k; i ++) {
        int x;
        cin >> x;
        spe.push_back (x);
        mp[x] = 1;
    }
    for (int i = 1; i <= m; i ++) {
        int u, v, w;
        cin >> u >> v >> w;
        if (ck.find ({u, v}) == ck.end ()) {
            ck[{u, v}] = w;
        }
        else {
            mini (ck[{u, v}], w);
        }
        w = ck[{u, v}];
        adj[u].push_back ({v, w});
        adj[v].push_back ({u, w});
        all.push_back ({u, v, w});        
    } 
    multiSources ();
    for (auto [u, v, w] : all) {
        nAll.push_back ({u, L[v].se, w + L[v].fi});
        nAll.push_back ({L[u].se, v, L[u].fi + w});
        //cout << L[u].se << ' ' << L[v].se << ' ' << L[u].fi + w + L[v].fi << '\n';
    }
    init ();
    sort (nAll.begin (), nAll.end (), cmpEdge);
    int cnt = 0, res = 0;
    //cout << getRoot (1) << ' ' << getRoot (2) << '\n';
    for (auto [u, v, w] : nAll) {
        //cout << u << ' ' << v << ' ' << w << '\n'; 
        if (getRoot (u) == getRoot (v)) {
            continue;
        }
        merge (u, v);
        res += w;
        int rt = getRoot (u);
        if (curS[rt] == k) {
            break;
        }
    }
    cout << res;
    return;
}

signed main () {
    cin.tie (nullptr) -> sync_with_stdio (false);
    if (fopen (task".inp", "r")) {
        freopen (task".inp", "r", stdin);
        freopen (task".out", "w", stdout);
    }
    int t = 1;
    //cin >> t;
    while (t --) {
        solve ();
    } 
    return 0;
}
// thfdgb

Compilation message (stderr)

cities.cpp: In function 'int main()':
cities.cpp:152:17: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  152 |         freopen (task".inp", "r", stdin);
      |         ~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~
cities.cpp:153:17: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  153 |         freopen (task".out", "w", stdout);
      |         ~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 0 / 22
• Subtask 2: 0 / 14
• Subtask 3: 0 / 15
• Subtask 4: 0 / 23
• Subtask 5: 0 / 26