PAT Basic 1001 害死人不偿命的(3n+1)猜想 (15 分)

#include <iostream>
#include <vector>
#include <algorithm>
using namespace std;
int main()
{
    int num,tmp,m;vector<int> val,ans;
    cin>>num;
    vector<int>::iterator posi;
    while(num--){
        cin>>tmp;
        val.push_back(tmp);
    }
    while(val.size()!=0){
        m=val[0];
        val.erase(val.begin());
        ans.push_back(m);
        while(m!=1){
            if(m%2==0) m/=2;
            else m=(3*m+1)/2;
            posi=find(val.begin(),val.end(),m);
            if(posi!=val.end()) val.erase(posi);
            posi=find(ans.begin(),ans.end(),m);
            if(posi!=ans.end()) ans.erase(posi);
        }
    }
    sort(ans.begin(),ans.end(),greater<int>());
    for(int i=0;i<ans.size();i++){
        cout<<ans[i];
        if(i!=(ans.size()-1)) cout<<" ";
    }
    return 0;
}