Vasily has a number a, which he wants to turn into a number b. For this purpose, he can do two types of operations:

• multiply the current number by 2 (that is, replace the number x by 2·x);
• append the digit 1 to the right of current number (that is, replace the number x by 10·x?+?1).

You need to help Vasily to transform the number a

Note that in this task you are not required to minimize the number of operations. It suffices to find any way to transform a into b.

The first line contains two positive integers a and b (1?≤?a?<?b

If there is no way to get b from a, print "NO" (without quotes).

Otherwise print three lines. On the first line print "YES" (without quotes). The second line should contain single integer k — the length of the transformation sequence. On the third line print the sequence of transformations x

• x1 should be equal to a,
• xk should be equal to b,
• xi should be obtained from xi?-?1 using any of two described operations (1?<?i?≤?k).

If there are multiple answers, print any of them.

2 162

YES
5
2 4 8 81 162 

4 42

NO

100 40021

YES
5
100 200 2001 4002 40021 

題意：就是從a變成b（*2或者的*10+1），可以就輸出具體變化

解法：額。。搜索一下嘛

 1 #include <iostream>
 2 #include <algorithm>
 3 #include <stdio.h>
 4 #include <cstring>
 5 using namespace std;
 6 int a[1000];
 7 long long n,m;
 8 int flag;
 9 int cnt;
10 void dfs(int cnt,long long x){
11 
12     a[cnt]=x;
13     if(x>m){
14         return;
15     }
16     if(x==m&&flag==0){
17         flag=1;
18         cout<<"YES"<<endl;
19         cout<<cnt<<endl;
20         for(int i=1;i<=cnt;i++){
21             cout<<a[i]<<" ";
22         }
23     }
24     dfs(cnt+1,x*10+1);
25     dfs(cnt+1,x*2);
26 }
27 int main(){
28     cin>>n>>m;
29     dfs(1,n);
30     if(flag==0){
31         cout<<"NO"<<endl;
32     }
33     return 0;
34 }

Technocup 2017 - Elimination Round 1 (Unofficially Open for Everyone, Rated for Div. 2) A