# 109 D

::: danger
所有程式碼皆不保證為正確解答
解題前請先看清楚題目，再自行修正以下程式碼使其符合題目要求:slightly_smiling_face:
如果抓到BUG也非常歡迎留言告訴大家怎麼修正喔(反白之後就能留言了)
:::

第一題

第二題

#include<iostream>
using namespace std;
int main(){
    while(true){
        cout<<"\t20506\t吳佩芸\n\td卷\t第二題\n";
        cout<<"輸入金額，算找回的錢\n";
        int payable, paid, change;
        cout<<"應付金額:";
        cin>>payable;
        cout<<"\n實際付款金額:";
        cin>>paid;
        if(paid<payable){
            cout<<"\n輸入錯誤\n";
        }else if(paid==payable){
            cout<<"不用找錢\n";
        }else{
            change=paid-payable;
            cout<<"應找"<<change<<"元\n";
            cout<<"1000元: "<<change/1000<<"張\n";
            change-=1000*(change/1000);
            cout<<"500元: "<<change/500<<"張\n";
            change-=500*(change/500);
            cout<<"100元: "<<change/100<<"張\n";
            change-=100*(change/100);
            cout<<"50元: "<<change/50<<"張\n";
            change-=50*(change/50);
            cout<<"10元: "<<change/10<<"張\n";
            change-=10*(change/10);
            cout<<"5元: "<<change/5<<"張\n";
            change-=5*(change/5);
            cout<<"1元: "<<change/1<<"張\n";
        }
    }
    return 0;
}

第三題

#include <iostream>
using namespace std;
int main()
{
    int i, j, n, sum = 0;
    while(true){
        cout<<"\t20506\t吳佩芸\n\td卷\t第三題\n";
        cout<<"請輸入n：";
        cin>>n;
        sum = 0;
        for(j = 1; j < n; j++){
            if( n%j == 0){
                sum += j;
            }
        }
        if(sum == n){
            cout<<n<<"為完美數\n";
        }else {
            cout<<n<<"不是完美數\n";
        }
    }
    return 0;
}

第四題

#include<iostream>
#include<time.h>
#include<cstdlib>
using namespace std;
int main(){
    int guess, ans, ub, lb;
    srand(time(NULL));
    ub=1000;
    lb=99;
    while(true){
        cout<<"\t20506\t吳佩芸\n\td卷\t第四題\n";
        cout<<"請在99到1000中猜一個數字\n";
        ans=99+rand()%(1000-99+1);
        while(cin>>guess){
        if(guess==ans){
            cout<<"correct\n";
            break;
        }else if(guess<lb || guess>ub){
            cout<<"error\n";
        }else if(guess>ans){
            ub=guess;
            cout<<lb<<"to "<<ub<<endl;
        }else{
            lb=guess;
            cout<<lb<<"to "<<ub<<endl;
        }
        }
    }
    return 0;
}

自訂範圍

#include<iostream>
#include<time.h>
#include<cstdlib>
using namespace std;
int main(){
    int guess, ans, ub, lb;
    srand(time(NULL));
    while(true){
        cout<<"\t20506\t吳佩芸\n\td卷\t第四題\n";
        cin>>lb>>ub;
        cout<<"請在"<<lb<<"到"<<ub<<"中猜一個數字\n";
        ans=lb+rand()%(ub-lb+1);
        while(cin>>guess){
        if(guess==ans){
            cout<<"correct\n";
            break;
        }else if(guess<lb || guess>ub){
            cout<<"error\n";
        }else if(guess>ans){
            ub=guess;
            cout<<lb<<"to "<<ub<<endl;
        }else{
            lb=guess;
            cout<<lb<<"to "<<ub<<endl;
        }
        }
    }
    return 0;
}