Submission #75743

#	Time	Username	Problem	Language	Result	Execution time	Memory
75743		polyfish	Cities (BOI16_cities)	C++14	100 / 100	4326 ms	81396 KiB

cities

//pantyhose(black) + glasses = infinity

#include <bits/stdc++.h>
using namespace std;

#define debug(x) cerr << #x << " = " << x << '\n';
#define BP() cerr << "OK!\n";
#define PR(A, n) {cerr << #A << " = "; for (int _=1; _<=n; ++_) cerr << A[_] << ' '; cerr << '\n';}
#define PR0(A, n) {cerr << #A << " = "; for (int _=0; _<n; ++_) cerr << A[_] << ' '; cerr << '\n';}
#define FILE_NAME "data"

typedef pair<int64_t, int> pairInts;

const int MAX_N = 100002;
const int MAX_K = 5;
const int64_t INF = 1e18;

int n, m, k, important_city[MAX_K];
int64_t f[1<<MAX_K][MAX_N];
vector<pairInts> g[MAX_N];
priority_queue<pairInts, vector<pairInts>, greater<pairInts> > pq;

void enter() {
    cin >> n >> k >> m;
    for (int i=0; i<k; ++i) {
        cin >> important_city[i];
    }
    for (int i=1; i<=m; ++i) {
        int u, v, w;
        cin >> u >> v >> w;
        g[u].push_back(make_pair(w, v));
        g[v].push_back(make_pair(w, u));
    }
}

void dijkstra(int x) {
    for (int i=1; i<=n; ++i)
        pq.push(make_pair(f[x][i], i));
    while (pq.size()) {
        int u = pq.top().second;
        int64_t du = pq.top().first;
        pq.pop();
        if (du!=f[x][u])
            continue;
        for (int i=0; i<g[u].size(); ++i) {
            int v = g[u][i].second, w = g[u][i].first;
            if (f[x][v]>f[x][u]+w) {
                pq.push(make_pair(f[x][v] = f[x][u] + w, v));
            }
        }
    }
}

void dp() {
    for (int x=0; x<(1<<k); ++x)
        for (int i=1; i<=n; ++i)
            f[x][i] = INF;
    for (int i=0; i<k; ++i)
        f[1<<i][important_city[i]] = 0;
    for (int x=0; x<(1<<k); ++x) {
        for (int u=1; u<=n; ++u) {
            for (int i=0; i<g[u].size(); ++i) {
                int v = g[u][i].second, w = g[u][i].first;
                for (int x2 = x; x2>0; x2 = (x2 - 1) & x) {
                    f[x][u] = min(f[x][u], f[x2][v] + f[x^x2][u] + w);
                }
            }
        }
        dijkstra(x);
    }
    int64_t res = INF;
    for (int i=1; i<=n; ++i)
        res = min(res, f[(1<<k)-1][i]);
    cout << res;
}

int main() {
	#ifdef OFFLINE_JUDGE
		freopen(FILE_NAME".inp", "r", stdin);
		freopen(FILE_NAME".out", "w", stdout);
	#endif
	ios::sync_with_stdio(0); cin.tie(0);
	enter();
	dp();
}

Compilation message (stderr)

cities.cpp: In function 'void dijkstra(int)':
cities.cpp:45:24: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
         for (int i=0; i<g[u].size(); ++i) {
                       ~^~~~~~~~~~~~
cities.cpp: In function 'void dp()':
cities.cpp:62:28: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
             for (int i=0; i<g[u].size(); ++i) {
                           ~^~~~~~~~~~~~

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