Submission #413606

#	Time	Username	Problem	Language	Result	Execution time	Memory
413606		iANikzad	007 (CEOI14_007)	C++14	100 / 100	331 ms	17936 KiB

007

#include<bits/stdc++.h>

using namespace std;

#define pb push_back
#define F first
#define S second
#define debug(x) cerr<<#x<<" :"<<x<<"\n"
#define all(x) x.begin(),x.end()
#define pii pair<int,int>
#define FAST ios_base::sync_with_stdio(false), cin.tie(), cout.tie();
//#define int long long

typedef long long ll;
typedef long double ld;

const int maxn = 2e5 + 7;
const int mod = 1e9 + 7;
const int INF = 1e9 + 7;
const int mlog = 20;
const int SQ = 400;

vector<int> adj[maxn];
int dis[4][maxn];

void bfs(int v,int dis[maxn])
{
    for(int i = 0; i < maxn; i++) dis[i] = +INF;
    dis[v] = 0;

    queue<int> q; q.push(v);

    while(!q.empty())
    {
        v = q.front(), q.pop();
        for(int u : adj[v]) if(dis[v] + 1 < dis[u]) dis[u] = dis[v] + 1, q.push(u);
    }
}

int32_t main()
{
    FAST;

    int n, m;
    cin >> n >> m;

    int s, d, a, b;
    cin >> s >> d >> a >> b;

    for(int i = 0;i < m; i++)
    {
        int u, v;
        cin >> u >> v;

        adj[u].pb(v), adj[v].pb(u);
    }

    bfs(d, dis[0]), bfs(s, dis[1]), bfs(a, dis[2]), bfs(b, dis[3]);

    int dif1 = dis[0][a] - dis[1][a];
    int dif2 = dis[0][b] - dis[1][b];

    if(min(dif1, dif2) < 0) return cout << -1 << "\n", 0;
    if(dif1 != dif2) return cout << min(dif1, dif2) << "\n", 0;

    int mxS, mxD;
    mxS = mxD = 0;

    for(int i = 1; i <= n; i++) if(dis[0][i] + dis[2][i] == dis[0][a] && dis[0][i] + dis[3][i] == dis[0][b]) mxD = max(mxD, dis[0][i]);
    for(int i = 1; i <= n; i++) if(dis[1][i] + dis[2][i] == dis[1][a] && dis[1][i] + dis[3][i] == dis[1][b]) mxS = max(mxS, dis[1][i]);

    cout << dif1 - (dif1 + mxS < mxD) << "\n";

    return 0;
}

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