Submission #58245

#	Time	Username	Problem	Language	Result	Execution time	Memory
58245		evpipis	007 (CEOI14_007)	C++14	30 / 100	861 ms	16684 KiB

007

#include <bits/stdc++.h>
using namespace std;

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

const int len = 2e5+5, inf = 1e9;
int dis[len], tim[len];
int n, m, s1, s2, t1, t2;
queue<int> myq;
vector<int> adj[len];

bool check(int x){
    for (int i = 1; i <= n; i++)
        dis[i] = inf;

    if (0 < tim[s2]+x)
        dis[s2] = 0, myq.push(s2);
    while (!myq.empty()){
        int u = myq.front();
        myq.pop();

        for (int j = 0; j < adj[u].size(); j++){
            int v = adj[u][j];
            if (dis[v] == inf && dis[u]+1 != tim[v]+x)
                dis[v] = dis[u]+1, myq.push(v);
        }
    }

    //return (dis[t1] == -1 && dis[t2] == -1);
    //if (dis[t1]+1 < tim[t1]+x || dis[t2]+1 < tim[t2]+x)
      //  return false;
    //return true;
    return (tim[t1]+x <= dis[t1] && tim[t2]+x <= dis[t2]);
}

int bs(){
    int l = 0, r = n, ans = -1;
    while (l <= r){
        int mid = (l+r)/2;
        if (check(mid))
            l = mid+1, ans = mid;
        else
            r = mid-1;
    }

    return ans;
}

int main(){
    scanf("%d %d %d %d %d %d", &n, &m, &s1, &s2, &t1, &t2);
    for (int i = 0; i < m; i++){
        int a, b;
        scanf("%d %d", &a, &b);
        adj[a].pb(b);
        adj[b].pb(a);
    }

    for (int i = 1; i <= n; i++)
        tim[i] = -1;

    tim[s1] = 0, myq.push(s1);
    while (!myq.empty()){
        int u = myq.front();
        myq.pop();

        for (int j = 0; j < adj[u].size(); j++){
            int v = adj[u][j];
            if (tim[v] == -1)
                tim[v] = tim[u]+1, myq.push(v);
        }
    }

    printf("%d\n", bs() - 1);
    return 0;
}

/*
9 10
9 8 1 2
1 2
2 3
3 1
2 4
4 5
5 2
5 7
7 6
7 8
7 9
*/

Compilation message (stderr)

007.cpp: In function 'bool check(int)':
007.cpp:27:27: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
         for (int j = 0; j < adj[u].size(); j++){
                         ~~^~~~~~~~~~~~~~~
007.cpp: In function 'int main()':
007.cpp:71:27: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
         for (int j = 0; j < adj[u].size(); j++){
                         ~~^~~~~~~~~~~~~~~
007.cpp:55:10: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
     scanf("%d %d %d %d %d %d", &n, &m, &s1, &s2, &t1, &t2);
     ~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
007.cpp:58:14: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
         scanf("%d %d", &a, &b);
         ~~~~~^~~~~~~~~~~~~~~~~

• Subtask 1: 9 / 30
• Subtask 2: 21 / 70