166 - Making Change

[oulongbin]

hi ,i am so confused.can someone tell why i always got WA??

Code: Select all

#include <iostream>
using namespace std;
#include <cstring> 
#include <cstdio>
#include <cmath> 
//#include <fstream>
//ifstream fin("in.txt");
//#define cin fin


int shop[501];
int min;
int money;
int numOfCoin[7];
int num;

void init()
{
	int i,j;
	int cnt;
	memset(shop,0,sizeof(shop));
	for(i=500;i>=5;i-=5)
	{
		j=i;
		cnt=0;
		if(j>=200)
		{
			cnt+=j/200;
			j%=200;
		}
		if(j>=100)
		{
			cnt+=j/100;
			j%=100;
		}
		if(j>=50)
		{
			cnt+=j/50;
			j%=50;
		}
		if(j>=20)
		{
			cnt+=j/20;
			j%=20;
		}
		if(j>=10)
		{
			cnt+=j/10;
			j%=10;
		}
		if(j>=5)
		{
			cnt+=j/5;
			j%=5;
		}
		shop[i]=cnt;
	}
}

void backtrack(int type,int cnt,int sum)
{
	if(sum>=money)
	{
		if(num+shop[sum-money]<min)
			min=num+shop[sum-money];
		return ;
	}
	if(type>6)
		return;
	if(cnt<numOfCoin[type])
	{
		switch(type)
		{
		case 1:sum+=5;break;
		case 2:sum+=10;break;
		case 3:sum+=20;break;
		case 4:sum+=50;break;
		case 5:sum+=100;break;
		case 6:sum+=200;break;
		}
		num++;
		backtrack(type,cnt+1,sum);
		switch(type)
		{
		case 1:sum-=5;break;
		case 2:sum-=10;break;
		case 3:sum-=20;break;
		case 4:sum-=50;break;
		case 5:sum-=100;break;
		case 6:sum-=200;break;
		}
		num--;
		backtrack(type+1,0,sum);
	}
	else
	{
		backtrack(type+1,0,sum);
	}
}

int main()
{
	int i,j;
	double temp;
	init();
	while(1)
	{
		j=0;
		for(i=1;i<7;i++)
		{
			cin>>numOfCoin[i];
			j+=numOfCoin[i];
		}
		if(j==0)
			break;
		cin>>temp;
		money=int(temp*1000)/10;
		min=99999999;
		num=0;
		backtrack(1,0,0);
		printf("%3d\n",min);
	}
	return 0;
}

in this sample:
0 5 1 0 1 9 1.55

my program output : 4
but i see someone output :3

which one is right??
thanks!

[jagadish]

the correct ans is 4 of course..but u fail a lot of cases pasted above

[oulongbin]

hi , jagadish. my program output the same answer pasted above, which one is wrong ??

[jagadish]

just pointing out a couple of of them..

0 0 0 1 1 2 4.05
0 1 0 0 0 1 1.65

my output :
6
4

yours:
3
1

[oulongbin]

hi,jagadish.thank you very much.i finally get AC.
it is the problem of precision.
i run the program well in VC,but wrong in gcc.

[El-idioto]

@Krzysztof Duleba

Your program is wrong.

The answer for entry 125 in your list is wrong:

0 5 1 0 1 9 1.55

Correct answer is 4, but your app gives 3.

[Krzysztof Duleba]

Indeed.

[mak(cse_DU)]

Thanks to Krzysztof Duleba.
For his input and output....
I count $20.00 as a maximum and got AC.

[Obaida]

i got accepted taking 10$ as maximum.

[Ahmad]

According to my Acc prog the Ans is

Code: Select all

  4
  5
  2
  3
  4
  3
  5
  4
  4
  3
  1
  2
  2
  1
  3
  3
  4
  4
  7
  4
  4
  1
  3
  3
  2
  1
  5
  2
  4
  2
  5
  3
  2
  6
  4
  9
  3
  3
  3
  2
  3
  3
  1
  2
  2
  3
  4
  3
  3
  3
  1
  1
  4
  6
  2
  3
  3
  3
  3
  2
  4
  4
  3
  3
  4
  2
  2
  4
  4
  2
  2
  3
  2
  3
  4
  4
  5
  1
  4
  2
  5
  5
  4
  2
  3
  3
  4
  5
  4
  4
  3
  4
  4
  2
  3
  2
  3
  4
  4
  2
  3
  4
  6
  5
  4
  3
  2
  2
  5
  3
  1
  2
  3
  3
  3
  5
  3
  2
  4
  2
  4
  3
  3
  1
  4
  3
  3
  4
  2
  3
  5
  3
  3
  5
  1
  3
  3
  3
  3
  1
  2
  2
  2
  4
  5
  4
  4
  3
  2
  3
  2
  2
  4
  2
  3
  2
  3
  4
  3
  6
  3
  2
  4
  3
  3
  4
  5
  4
  5
  3
  5
  6
  3
  4
  2
  5
  2
  3
  6
  2
  3
  1
  3
  3
  3
  3
  2
  4
  3
  3
  4
  1
  2
  2
  5
  2
  1
  3
  3
  4

Good Luck

[@li_kuet]

Try this case :

Code: Select all

2 2 2 2 2 1 4.05
0 0 0 0 0 0

Correct answer is 4

[kaban]

Thus if we need to pay 55c, and we do not hold a 50c coin, we could pay this as 2*20c + 10c + 5c to make a total of 4 coins. If we tender $1 we will receive 45c in change which also involves 4 coins, but if we tender $1.05 ($1 + 5c), we get 50c change and the total number of coins that changes hands is only 3.

I m not asking for solution , I don't get what example is saying:

so, we need to pay 55c , coins = {5,10,20} , 55c = 2*2 + 1*10 + 1*5 - 4 coins.

But what is next ? "if we tender 1$ we will receive 45c? what does it mean ? 1 - 45 = 55 ?

and the last is 1.05?

can someone give a bit more detail? i dont' understand the question

[brianfry713]

For the first sample input the bill is .95, you pay $1 and get back .05, so 2 total coins change hands.
For the second sample input the bill is .55, you pay $1 and .05 and get back .50, so 3 total coins change hands.

There are many ways to pay the bill and receive change, the goal of this problem is to minimize the sum of the number of coins you pay plus coins received.

Also check out
http://online-judge.uva.es/board/viewtopic.php?t=6026

[jddantes]

Why is mine RE?

Code: Select all

#include <stdio.h>

int val[] = {5,10,20,50,100,200};
int coins[101] ={};
int main()
{
    coins[1] = 1;
    int i;
    for(i=2; i<101; i++)
    {
        coins[i] = 1000000;

        int num = i*5;
        int j;
        for(j=0; val[j] <= num; j++)
        {
            if(coins[(num - val[j])/5] + 1 < coins[i])
            {
                coins[i] = coins[(num-val[j])/5] + 1;
            }
        }
    }
    /*
    for(i=1; i<100; i++)
    {
        printf("%d coins to make %d\n",coins[i],i*5);
    }
    */
    while(1)
    {
        int hand[6] ={};
        int total = 0;
        for(i=0; i<6; i++)
        {
            scanf("%d",&hand[i]);
            total+=hand[i]*val[i];
        }

        if(hand[0] == 0 && hand[1] == 0 && hand[2] == 0 && hand[3] == 0 && hand[4] == 0 && hand[5] == 0)
            return 0;

        float ff;
        scanf("%f",&ff);
        ff *= 100;
        int num = (float)ff;
        //printf("Num is %d\n",num);
        //Get min ans:
        //For each amount you can make greater than or eqaul to num, let's call this pay
        //cp = min coins you have for pay
        //ans = cp + coins[pay-num]
        int pay_arr[total/5+1];
        for(i=num/5; i<total/5 +1; i++)
        {
            if(i*5 < num)
                pay_arr[i] = 0;
            else
            {
                pay_arr[i] = 1000000;
            }
        }

        int a,b,c,d,e,f;
        for(a=0; a<=hand[0]; a++)
        {
            for(b=0; b<=hand[1]; b++)
            {
                for(c=0; c<=hand[2]; c++)
                {
                    for(d=0; d<=hand[3]; d++)
                    {
                        for(e=0; e<=hand[4]; e++)
                        {
                            for(f=0; f<=hand[5]; f++)
                            {

                                int pay = a*val[0] + b*val[1] + c*val[2] + d*val[3] + e*val[4] + f*val[5];

                                if(pay<num)
                                    continue;

                                int num_coins = a + b + c + d + e + f;
                                //printf("I can make %d using %d coins\n",pay,num_coins);
                                if(num_coins < pay_arr[pay/5])
                                {
                                    pay_arr[pay/5] = num_coins;
                                    //printf("OPTIMAL I can make %d using %d coins\n",pay,pay_arr[pay/5]);
                                }
                            }
                        }
                    }
                }
            }
        }
        /*
        for(i=num/5; i<total/5 +1; i++)
        {
            if(pay_arr[i] < 1000000)
            {
                printf("I can make %d using %d coins\n",i*5,pay_arr[i]);
            }
        }
        */
        int min_ans = 1000000;
        for(i=num/5; i<total/5 + 1; i++)
        {
            if(pay_arr[i]==1000000)
                continue;
            int ans = pay_arr[i] + coins[(i*5-num)/5];
            //printf("I pay %d (%d coins) get %d change (%d coins) for a total of %d coins used\n",i*5,pay_arr[i],i*5-num,coins[(i*5-num)/5],pay_arr[i]+coins[(i*5-num)/5]);
            if(ans<min_ans)
                min_ans = ans;
        }
        printf("%3d\n",min_ans);
    }
    return 0;

}

[brianfry713]

On the sample input, line 15 of your code:
for(j=0; val[j] <= num; j++)
Is throwing a seg fault as j increases past the end of the val array.