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  1. #include<bits/stdc++.h>
  2. using namespace std;
  3.  
  4. long long n,m;
  5. bool visited[200005];
  6.  
  7. void bfs(long long n, long long m, bool visited[])
  8. {
  9.     queue<long long> q;
  10.  
  11.     q.push(n);
  12.     visited[n] = true;
  13.  
  14.     long long level = 0;
  15.  
  16.     while (!q.empty())
  17.     {
  18.         long long sz = q.size();
  19.         level++;
  20.  
  21.         while (sz--)
  22.         {
  23.             long long t = q.front();
  24.             q.pop();
  25.  
  26.             long long t1 = t*2;
  27.             long long t2 = t-1;
  28.  
  29.             if (t1 == m || t2 == m)
  30.             {
  31.                 cout << level;
  32.                 return;
  33.             }
  34.  
  35.             if (t1 >= 0 && t1 <= 100000 && !visited[t1])
  36.             {
  37.                 visited[t1] = true;
  38.                 q.push(t1);
  39.             }
  40.  
  41.             if (t2 >= 0 && !visited[t2])
  42.             {
  43.                 visited[t2] = true;
  44.                 q.push(t2);
  45.             }
  46.         }
  47.     }
  48. }
  49.  
  50. void input()
  51. {
  52.     cin >> n >> m;
  53. }
  54.  
  55. void solve()
  56. {
  57.     if (n == m)
  58.     {
  59.         cout << 0;
  60.         return;
  61.     }
  62.  
  63.     bfs(n, m, visited);
  64. }
  65.  
  66. int main()
  67. {
  68.     ios_base::sync_with_stdio(0);
  69.     cin.tie(0);
  70.  
  71.     input();
  72.     solve();
  73. }
  74.  
  75.  
Success #stdin #stdout 0s 5320KB
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https://ideone.com/NWEVNP
language:
C++14 (gcc 8.3)
created:
2 days ago
visibility:
public

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