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  1. #include <bits/stdc++.h>
  2. using namespace std;
  3. #define prev aaaa
  4. const int MAX_N = 200000;
  5. int n, k, visited[MAX_N + 4], prev[MAX_N + 4];
  6. queue<int> q;
  7. vector<int> v;
  8. int main(){
  9.     cin >> n >> k;
  10.     if(n == k){
  11.         cout << 0 << '\n' << n << '\n';
  12.         return 0;
  13.     }
  14.     q.push(n);
  15.     visited[n] = 1;
  16.     while(q.size()){
  17.         int here = q.front();
  18.         q.pop();
  19.  
  20.         if(here == k){
  21.             break;
  22.         }
  23.  
  24.         for(int next : {here + 1, here - 1, here * 2}){
  25.             if(next < 0 || next > MAX_N || visited[next]) continue;
  26.             visited[next] = visited[here] + 1;
  27.             prev[next] = here;
  28.             q.push(next);
  29.         }
  30.     }
  31.  
  32.     for(int i = k; i != n; i = prev[i]){
  33.         v.push_back(i);
  34.     }
  35.     reverse(v.begin(), v.end());
  36.  
  37.     cout << visited[k] - 1 << '\n';
  38.     for(int b : v) cout << b << ' ';
  39. }
Success #stdin #stdout 0s 5316KB
comments (?)
stdin
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5 17
stdout
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4
4 8 16 17
https://ideone.com/szTYIO
language:
C++ (gcc 8.3)
created:
2 days ago
visibility:
public

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