Submission #82419

#	Time	Username	Problem	Language	Result	Execution time	Memory
82419		Flying_dragon_02	007 (CEOI14_007)	C++14	0 / 100	373 ms	16524 KiB

007

#include<bits/stdc++.h>

using namespace std;

#define pb push_back
#define fi first
#define se second
typedef pair<int, int> ii;

const int N = 2e5 + 5, inf = 1e9 + 123;
int n, m, src[2], a[2], d[2][N], l = -1, r = 6e5 + 5;
vector<int> gr[N];

void dijkstra (bool _) {
    for (int i = 1; i <= n; ++i) d[_][i] = inf;
    d[_][ src[_] ] = 0;
    priority_queue<ii, vector<ii>, greater<ii> > pq; pq.push(ii(d[_][ src[_] ], src[_]) );
    while (!pq.empty() ) {
        ii tmp = pq.top(); pq.pop();
        int u = tmp.se;
        if (tmp.fi > d[_][u]) continue ;
        for (int v : gr[u]) {
            if (d[_][v] > d[_][u] + 1) {
                d[_][v] = d[_][u] + 1;
                pq.push(ii(d[_][v], v) );
            }
        }
    }
}

bool check (int Time) {
    d[1][ a[0] ] -= Time;
    d[1][ a[1] ] -= Time;
    if (d[0][ a[0] ] > d[1][ a[0] ] || d[0][ a[1] ] > d[1][ a[1] ]) {
        d[1][ a[0] ] += Time;
        d[1][ a[1] ] += Time;
        return false;
    }

    d[1][ a[0] ] += Time;
    d[1][ a[1] ] += Time;
    return true;
}

int main () {
    ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
    //freopen("SPY.INP", "r", stdin);
    //freopen("SPY.OUT", "w", stdout);
    cin >> n >> m;
    cin >> src[0] >> src[1] >> a[0] >> a[1];
    while (m --) {
        int u, v; cin >> u >> v;
        gr[u].pb(v); gr[v].pb(u);
    }

    dijkstra(0);
    dijkstra(1);

    while (l < r) {
        int mid = (l + r + 1) / 2;
        if (check(mid) ) l = mid;
        else r = mid - 1;
    }

    cout << l;

    return 0;
}

• Subtask 1: 0 / 30
• Subtask 2: 0 / 70