时间限制：1 秒

内存限制：32 兆

特殊判题：否

提交：939

解决：489

题目描述：

Larry graduated this year and finally has a job. He's making a lot of money, but somehow never seems to have enough. Larry has decided that he needs to grab hold of his financial portfolio and solve his financing problems. The first step is to figure out what's been going on with his money. Larry has his bank account statements and wants to see how much money he has. Help Larry by writing a program to take his closing balance from each of the past twelve months and calculate his average account balance.

输入：

Each case will be twelve lines. Each line will contain the closing balance of his bank account for a particular month. Each number will be positive and displayed to the penny. No dollar sign will be included.

输出：

For each case, the output will be a single number, the average (mean) of the closing balances for the twelve months. It will be rounded to the nearest penny, preceded immediately by a dollar sign, and followed by the end-of-line. There will be no other spaces or characters in the output.

样例输入：

100.00

489.12

12454.12

1234.10

823.05

109.20

5.27

1542.25

839.18

83.99

1295.01

1.75

样例输出：

$1581.42

来源：

2009年北京大学计算机研究生机试真题

思路：

求平均数。

代码：

#include

int main(void)

{

int n, i;

double cost;

double sum;

while (scanf("%lf", &cost) != EOF)

{

sum = cost;

for(i=1; i<12; i++)

{

scanf("%lf", &cost);

sum += cost;

}

printf("$%.2lf\n", sum/12);

}

return 0;

}

/**************************************************************

Problem: 1141

User: liangrx06

Language: C

Result: Accepted

Time:0 ms

Memory:912 kb

****************************************************************/