题解 | #2的幂次方#

#include <iostream>
#include <vector>
using namespace std;

void Q(int a) {
    vector<int> vec;//0001-8
    while (a != 0) {
        vec.push_back(a % 2);
        a /= 2;
    }
    
    for(int i=vec.size()-1;i>=0;i--)
    {
        if(i==0&&vec[i]==1)cout<<"2(0)";
        else if(i==1&&vec[i]==1&&vec[0]==1)cout<<"2+";
        else if(i==1&&vec[i]==1&&vec[0]==0)cout<<"2";
        else if(i==2&&vec[i]==1&&(vec[0]==1||vec[1]==1))cout<<"2(2)+";
        else if(i==2&&vec[i]==1&&(vec[0]==0&&vec[1]==0))cout<<"2(2)";
        else if(vec[i]==1)
        {
            int j=i-1;
            int flag=0;//要不要输出+
            while(j>=0)
            {
                if(vec[j]==1)
                {
                    flag=1;break;
                }
                j--;
            }

            cout<<"2(";
            Q(i);
            cout<<")";
            if(flag==1)cout<<"+";
        }
    }

}
int main() {
    int a;
    while (cin >> a) {
        if(a==1)cout<<"2(0)"<<endl;
        else if(a==2)cout<<"2"<<endl;
        else if(a==3)cout<<"2+2(0)"<<endl;
        else if(a==4)cout<<"2+2"<<endl;
        else{
            Q(a);
            cout << endl;   
        }
        

    }
}