Submission #1118362

#	Time	Username	Problem	Language	Result	Execution time	Memory
1118362		gdragon	Network (BOI15_net)	C++17	0 / 100	5 ms	5472 KiB

net

#include <bits/stdc++.h>
using namespace std;
#define TASK "long"
#define fi first
#define se second
#define ll long long
#define pb push_back
#define ALL(x) (x).begin(), (x).end()
#define GETBIT(mask, i) ((mask) >> (i) & 1)
#define MASK(i) ((1LL) << (i))
#define SZ(x) ((int)(x).size())
#define mp make_pair
#define CNTBIT(mask) __builtin_popcount(mask)
template<class X, class Y> bool maximize(X &x, Y y){ if (x < y) {x = y; return true;} return false;};
template<class X, class Y> bool minimize(X &x, Y y){ if (x > y) {x = y; return true;} return false;};
typedef pair<int, int> ii;
const int N = 1e5 + 5;
const int M = 5e5 + 5;
const int inf = 1e9 + 7;
const long long INF = (long long)1e18 + 7;
const int mod = 1e9 + 7;
struct DSU {
    int n;
    vector<int> par;
    vector<vector<int>> sz;
    DSU(int _n = 0) {
        n = _n;
        par.assign(n + 5, -1);
        sz.assign(n + 2, vector<int>());
        for(int i = 1; i <= n; i++) sz[i].push_back(i);
    }
    int root(int v) {
        return par[v] < 0 ? v : (par[v] = root(par[v]));
    }
    bool join(int x, int y) {
        if (par[y] < par[x]) swap(x, y);
        par[x] += par[y];
        for(int p: sz[y]) sz[x].push_back(p);
        sz[y].clear();
        par[y] = x;
        return true;
    }
} dsu;
vector<ii> adj[N];
int n, m, q, numNpp;
vector<int> Npps, val;
int d[N];
pair<int, int> e[M];
vector<ii> queries[N];
void read() {
    cin >> n >> m;
    for(int i = 1; i <= m; i++) {
        int u, v, c; cin >> u >> v >> c;
        adj[u].push_back({v, c});
        adj[v].push_back({u, c});
        e[i] = {u, v};
    }
    cin >> numNpp;
    Npps.assign(numNpp, 0);
    for(int &i: Npps) cin >> i;
}
void calDistToNpp() {
    priority_queue<ii, vector<ii>, greater<ii>> heap;
    memset(d, 0x3f, sizeof(d));
    for(int i: Npps) {
        heap.push({0, i});
        d[i] = 0;
    }
    while(!heap.empty()) {
        ii tmp = heap.top(); heap.pop();
        int u = tmp.se;
        int du = tmp.fi;
        if (du != d[u]) continue;
        for(auto [v, c]: adj[u]) {
            if (minimize(d[v], d[u] + c)) {
                heap.push(mp(d[v], v));
            }
        }
    }
}
int ans[N];
void solve() {
    calDistToNpp();
    cin >> q;
    for(int i = 1; i <= q; i++) {
        int u, v; cin >> u >> v;
        queries[u].push_back({v, i});
        queries[v].push_back({u, i});
    }
    sort(e + 1, e + m + 1, [&](const ii &x, const ii &y) {
        return min(d[x.fi], d[x.se]) > min(d[y.fi], d[y.se]);
    });
    dsu = DSU(n);
    for(int i = 1; i <= m; i++) {
        int r1 = dsu.root(e[i].fi), r2 = dsu.root(e[i].se);
        if (r1 == r2) continue;
        int mn = min(d[e[i].fi], d[e[i].se]);
        if (SZ(dsu.sz[r1]) > SZ(dsu.sz[r2])) swap(r1, r2);
        for(int x: dsu.sz[r1]) {
            for(auto [y, id]: queries[x]) if (ans[id] == 0) {
                if (dsu.root(y) == r2) {
                    ans[id] = mn;
                }
            }
        }
        dsu.join(r1, r2);
    }
    for(int i = 1; i <= q; i++) cout << ans[i] << endl;
}
signed main() {
    ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
    if (fopen(TASK".inp", "r")) {
        freopen(TASK".inp", "r", stdin);
        freopen(TASK".out", "w", stdout);
    }
    int test = 1;
    // cin >> test;
    while(test--) {
        read();
        solve();
    }
    return 0;
}

// rmq - rmq2d
// hash
// fw - fw2d
// segtree

Compilation message (stderr)

net.cpp: In function 'int main()':
net.cpp:113:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  113 |         freopen(TASK".inp", "r", stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~
net.cpp:114:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  114 |         freopen(TASK".out", "w", stdout);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 0 / 18
• Subtask 2: 0 / 45
• Subtask 3: 0 / 37