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  1. #include <iostream>
  2. #include <stdio.h>
  3. #include <cmath>
  4. #include <string>
  5. #include <vector>
  6. #include <stack>
  7. #include <queue>
  8. #include <cassert>
  9. #include <ctime>
  10. #include <cstdlib>
  11. #include <algorithm>
  12. #define Pi 3.14159
  13. #define vi vector<int>
  14. #define pi pair<int,int>
  15. #define si stack<int>
  16.  
  17. typedef long long int ll;
  18. using namespace std;
  19.  
  20. bool b[3501][3501]={0};
  21.  
  22. int main ()
  23. {
  24.     int n,m;
  25.     cin >>n>>m;
  26.     int u,v;
  27.     for (int i  =1;i<= m;i++)
  28.     {
  29.         scanf("%d",&u);
  30.         scanf("%d",&v);
  31.         b[u][v]=b[v][u]=1;
  32.     }
  33.     // input completed.
  34.     int dist[n+1];
  35.  
  36.     int h,V;
  37.     cin >>h>>V;
  38.     dist[h]=0;
  39.     //cout<<"hero "<<h<<" "<<V<<endl;
  40.     queue<int> q;
  41.     bool  bfs[3501];
  42.     for (int  i=1;i<= n;i++)bfs[i]=1;
  43.     q.push(h);
  44.     bfs[h]=0;
  45.     while (!q.empty())
  46.     {
  47.         int top = q.front();
  48.        // cout<<top<<endl;
  49.         q.pop();
  50.         for (int i = 1 ;i <= 3500;i++)
  51.         {
  52.             if(bfs[i] && b[i][top])
  53.             {
  54.                 int x = i;
  55.                 dist[i] = dist[top] +1;
  56.                 if(x == V){cout<<dist[x]<<endl;return 0;}
  57.                 bfs[x]=0;
  58.                 q.push(x);
  59.             }
  60.         }
  61.     }
  62.     cout<<0<<endl;
  63. }
  64.  
  65.  
Success #stdin #stdout 0s 15448KB
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https://ideone.com/GqTc6k
language:
C++ (gcc 8.3)
created:
10 years ago
visibility:
public

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