硬币那道题我是第一题。。。想着是拿动态规划做，大家帮我看看，为什么min_num就是不变呢==我觉得我逻辑没问题啊ORZ

#include <iostream>

using namespace std;

void find_equal(int num1,int num2,int n,int total1,int total2,int &min_num){

  if(num1==total1&&num2==total2){

    if(n<min_num)

      min_num=n;

    return;

  }

  if(num1>total1)

    return;

  n=n+1;

  find_equal(num1*2,num2*2,n,total1,total2,min_num);

  find_equal(num1+1,num2*2,n,total1,total2,min_num);

}

int main() {

    int a,b,A,B;

  while(cin >> a >> b>>A>>B){

    int min_num=100000;

    find_equal(a,b,0,A,B,min_num);

    if(min_num!=100000)

      cout<<min_num<<endl;

    else

      cout<<"-1"<<endl;

  }

}