Submission #1028813

#	Time	Username	Problem	Language	Result	Execution time	Memory
1028813		phoenix	Cities (BOI16_cities)	C++17	100 / 100	1628 ms	47164 KiB

cities

#include <bits/stdc++.h>

using namespace std;
using ll = long long;

const int N = 100100;
const int M = 200200;
const ll INF = 1e15;

int n, m, k;
vector<pair<int, ll>> g[N];
int special[5];

int main() {
    ios::sync_with_stdio(0);
    cin.tie(0);
    
    cin >> n >> k >> m;
    
    for (int i = 0; i < k; i++) {
        cin >> special[i];
        special[i]--;
    }


    for (int i = 0; i < m; i++) {
        int u, v, w;
        cin >> u >> v >> w;
        u--, v--;
        g[u].push_back({v, w});
        g[v].push_back({u, w});
    }
    ll dp[(1 << k)][n] = {};
    for (int i = 1; i < (1 << k); i++) 
        for (int j = 0; j < n; j++)
            dp[i][j] = INF;
    
    for (int i = 0; i < k; i++)
        dp[(1 << i)][special[i]] = 0;
    
    for (int msk = 1; msk < (1 << k); msk++) {
        for (int v = 0; v < n; v++) 
            for (int sub = msk; sub && sub > (msk ^ sub); sub = (msk & sub - 1)) 
                dp[msk][v] = min(dp[msk][v], dp[sub][v] + dp[(msk ^ sub)][v]);
        priority_queue<pair<ll, int>> pq;
        for (int i = 0; i < n; i++)
            pq.push({-dp[msk][i], i});
        while (!pq.empty()) {
            auto [d, x] = pq.top();
            pq.pop();
            if (dp[msk][x] != -d) continue;;
            for (auto [to, w] : g[x]) {
                if (dp[msk][to] > dp[msk][x] + w) {
                    dp[msk][to] = dp[msk][x] + w;
                    pq.push({-dp[msk][to], to});
                }
            }
        } 
    }
    cout << *min_element(dp[(1 << k) - 1], dp[(1 << k) - 1] + n);
}

Compilation message (stderr)

cities.cpp: In function 'int main()':
cities.cpp:43:76: warning: suggest parentheses around '-' in operand of '&' [-Wparentheses]
   43 |             for (int sub = msk; sub && sub > (msk ^ sub); sub = (msk & sub - 1))
      |                                                                        ~~~~^~~

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