Submission #153478

#	Time	Username	Problem	Language	Result	Execution time	Memory
153478		Mercenary	007 (CEOI14_007)	C++14	100 / 100	354 ms	24816 KiB

007

#include<bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/trie_policy.hpp>

#define pb push_back
#define mp make_pair
#define taskname "A"

using namespace std;
using namespace __gnu_pbds;

typedef long long ll;
typedef long double ld;
typedef pair<int,int> ii;
typedef tree <int,null_type,less<int>,rb_tree_tag,tree_order_statistics_node_update> ordered_set;

const int maxn = 250000 + 5;
int n , m , s , d , a , b;
vector<int> adj[maxn];
int ds[maxn] , dd[maxn] , da[maxn] , db[maxn];
int main()
{
    ios_base::sync_with_stdio(0);
    cin.tie(0);
    if(fopen(taskname".INP","r")){
		freopen(taskname".INP", "r",stdin);
		freopen(taskname".OUT", "w",stdout);
    }
    cin >> n >> m >> s >> d >> a >> b;
    for(int i = 1 ; i <= m ; ++i){
        int u , v;cin >> u >> v;
        adj[u].pb(v);
        adj[v].pb(u);
    }
    auto BFS = [&](int u , int d[maxn]){
        queue<int> q;
        fill_n(d,maxn,-1);
        d[u] = 0;
        q.push(u);
        while(q.size()){
            int u = q.front();q.pop();
            for(int c : adj[u]){
                if(d[c] == -1){
                    d[c] = d[u] + 1;
                    q.push(c);
                }
            }
        }
    };
    BFS(s , ds);BFS(d , dd);BFS(a , da);BFS(b , db);
    if(dd[a] + 1 <= ds[a] || dd[b] + 1 <= ds[b]){
        return cout << -1 , 0;
    }
    int res = 0;
    if(dd[a] - ds[a] == dd[b] - ds[b]){
        int sres = 0  , dres = 0;
        for(int i = 1 ; i <= n ; ++i){
            if(ds[a] == da[i] + ds[i] && ds[b] == db[i] + ds[i]){
                sres = max(sres , ds[i]);
            }
            if(dd[a] == da[i] + dd[i] && dd[b] == db[i] + dd[i]){
                dres = max(dres , dd[i]);
            }
        }
//        cout << sres << " " << dres << endl;
        cout << dd[a] - ds[a] - (sres + dd[a] - ds[a] < dres);
    }else{
        cout << min(dd[a] - ds[a] , dd[b] - ds[b]);
    }
}

Compilation message (stderr)

007.cpp: In function 'int main()':
007.cpp:54:9: warning: unused variable 'res' [-Wunused-variable]
     int res = 0;
         ^~~
007.cpp:26:10: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result]
   freopen(taskname".INP", "r",stdin);
   ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~
007.cpp:27:10: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result]
   freopen(taskname".OUT", "w",stdout);
   ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~

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