Submission #26252

#	Time	Username	Problem	Language	Result	Execution time	Memory
26252		sgtlaugh	Cities (BOI16_cities)	C++14	100 / 100	3019 ms	43876 KiB

cities

#include <stdio.h>
#include <bits/stdtr1c++.h>

#define MAXK 5
#define MAXN 100010
#define clr(ar) memset(ar, 0, sizeof(ar))
#define read() freopen("lol.txt", "r", stdin)
#define dbg(x) cout << #x << " = " << x << endl
#define ran(a, b) ((((rand() << 15) ^ rand()) % ((b) - (a) + 1)) + (a))

using namespace std;

const long long INF = 1LL << 60;

bitset <MAXN> visited;
int n, k, m, special[MAXK];
long long dis[1 << MAXK][MAXN];
vector <pair<int, int> > graph[MAXN];

void dijkstra(long long dis[MAXN]){
    int i, j, v, w;
    priority_queue <pair<long long, int> > PQ;
    for (i = 1; i <= n; i++){
        visited[i] = 0;
        if (dis[i] < INF) PQ.push(make_pair(-dis[i], i));
    }

    while (!PQ.empty()){
        pair <long long, int> cur = PQ.top();
        PQ.pop();

        i = cur.second;
        if (visited[i]) continue;
        visited[i] = 1;

        for (j = 0; j < graph[i].size(); j++){
            v = graph[i][j].first, w = graph[i][j].second;
            if (dis[v] >  dis[i] + w){
                dis[v] = dis[i] + w;
                PQ.push(make_pair(-dis[v], v));
            }
        }
    }
}

long long minimumSteinerTree(){
    int i, j, mask, submask;

    for (mask = 1; mask < (1 << k); mask++){
        for (i = 1; i <= n; i++) dis[mask][i] = INF;
        if (__builtin_popcount(mask) == 1){
            dis[mask][special[31 - __builtin_clz(mask)]] = 0;
        }
        else{
            for (i = 1; i <= n; i++){
                for (submask = mask - 1; submask >= (submask ^ mask); submask = (submask - 1) & mask){
                    dis[mask][i] = min(dis[mask][i], dis[submask][i] + dis[submask ^ mask][i]);
                }
            }
        }
        dijkstra(dis[mask]);
    }

    return *std::min_element(dis[mask - 1] + 1, dis[mask - 1] + 1 + n);
}

int main(){
    int i, j, u, v, w;

    while (scanf("%d %d %d", &n, &k, &m) != EOF){
        for (i = 0; i < MAXN; i++) graph[i].clear();
        for (i = 0; i < k; i++) scanf("%d", &special[i]);

        for (i = 0; i < m; i++){
            scanf("%d %d %d", &u, &v, &w);
            graph[u].push_back(make_pair(v, w));
            graph[v].push_back(make_pair(u, w));
        }

        printf("%lld\n", minimumSteinerTree());
    }
    return 0;
}

Compilation message (stderr)

cities.cpp: In function 'void dijkstra(long long int*)':
cities.cpp:36:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
         for (j = 0; j < graph[i].size(); j++){
                       ^
cities.cpp: In function 'long long int minimumSteinerTree()':
cities.cpp:47:12: warning: unused variable 'j' [-Wunused-variable]
     int i, j, mask, submask;
            ^
cities.cpp: In function 'int main()':
cities.cpp:68:12: warning: unused variable 'j' [-Wunused-variable]
     int i, j, u, v, w;
            ^
cities.cpp:72:57: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
         for (i = 0; i < k; i++) scanf("%d", &special[i]);
                                                         ^
cities.cpp:75:42: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
             scanf("%d %d %d", &u, &v, &w);
                                          ^

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