UVa 10137 The Trip

引用某個解題者的話：This problem IS a trip.

乍看很簡單，但是很容易在浮點數精確度上吃悶虧。
最後我全部轉成int來運算，確保一切在掌握之內。

兩點提醒
1. 平均開銷算出來以後要四捨五入到小數第二位(1 cent)
2. 因為平均開銷不精確，所以exchange amount 要統計兩個，輸出小的那一個。

	/**
	* UVa 10137 (AC)
	* Author: chchwy
	* Last Modified: 2009.03.26
	*/
	#include<iostream>
	/* read expense as cent. ex. 1.23 dollar => 123 cent */
	int getExpense()
	{
	int i = 0;
	char c;
	char buf[16];
	while ((c = getchar()) != '\n')
	{
	if (c != '.')
	buf[i++] = c;
	}
	buf[i] = 0;
	return atoi(buf);
	}
	int main()
	{
	#ifndef ONLINE_JUDGE
	freopen("10137.in", "r", stdin);
	//freopen("10137.out","w",stdout);
	#endif
	int stu[1000]; //expense of each student
	int stuNum; //number of students
	/* for each case */
	while (scanf("%d ", &stuNum) == 1)
	{
	if (stuNum == 0) break;
	//compute the average
	int sum = 0;
	for (int i = 0; i < stuNum; ++i)
	{
	stu[i] = getExpense();
	sum += stu[i];
	}
	int avg = ((double)sum / stuNum) + 0.5;
	//compute the exchange amount
	int exchg1 = 0, exchg2 = 0;
	for (int i = 0; i < stuNum; ++i)
	{
	if (stu[i] > avg)
	exchg1 += stu[i] - avg;
	else if (stu[i] < avg)
	exchg2 += avg - stu[i];
	}
	double rslt = (exchg1 < exchg2) ? exchg1 : exchg2;
	rslt /= 100;
	printf("$%.2lf\n", rslt);
	}
	return 0;
	}

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