codeforces1469D Ceil Divisions (construction questions, law questions)

Portal
problem solution: in fact, it is a problem constructed by discovering the rules, and the problem needs $n+The\; 5-$ step construction is completed, then there must be many operations in the$The$ number of$i$ divided by the$i+1$ number, you can find that if a large number wants to drop, the least is$2$ step operation, in fact, it is an extra$1$ step operation, then up to$There\; are\; 5$ numbers. These numbers are bound to be related. Lenovo can also think of operations under the radical sign. You can see$2e5$ can be changed to2 2 withup to three or four root signs$2$ out.

int n;
vector<pair<int,int> >ans;
int main(){
    
    
    #ifdef io
    freopen("in.txt","r",stdin);
    freopen("out.txt","w",stdout);
    #endif
    rush(){
    
    
        cin>>n;
        ans.clear();
        while(n!=2){
    
    
            int next=ceil(sqrt(1.0*n));
            rep(i,max(3,next+1),n-1)ans.push_back({
    
    i,i+1});
            ans.push_back({
    
    n,next});
            ans.push_back({
    
    n,ceil(n*1.0/next)});
            if(next==2)break;
            else n=next;
        }
        int len=ans.size();
        pf(len);
        rep(i,0,ans.size()-1)pf2(ans[i].fi,ans[i].se);
    }
    return 0;
}