1108 Finding Average(20 分)
The basic task is simple: given N real numbers, you are supposed to calculate their average. But what makes it complicated is that some of the input numbers might not be legal. A legal input is a real number in [−1000,1000] and is accurate up to no more than 2 decimal places. When you calculate the average, those illegal numbers must not be counted in.
Input Specification:
Each input file contains one test case. For each case, the first line gives a positive integer N (≤100). Then N numbers are given in the next line, separated by one space.
Output Specification:
For each illegal input number, print in a line ERROR: X is not a legal number
where X
is the input. Then finally print in a line the result: The average of K numbers is Y
where K
is the number of legal inputs and Y
is their average, accurate to 2 decimal places. In case the average cannot be calculated, output Undefined
instead of Y
. In case K
is only 1, output The average of 1 number is Y
instead.
Sample Input 1:
7
5 -3.2 aaa 9999 2.3.4 7.123 2.35
Sample Output 1:
ERROR: aaa is not a legal number
ERROR: 9999 is not a legal number
ERROR: 2.3.4 is not a legal number
ERROR: 7.123 is not a legal number
The average of 3 numbers is 1.38
Sample Input 2:
2
aaa -9999
Sample Output 2:
ERROR: aaa is not a legal number
ERROR: -9999 is not a legal number
The average of 0 numbers is Undefined
我的天 20分的暴力题吓得我直打哆嗦。。。。
code
#pragma warning(disable:4996)
#include <iostream>
#include <string>
#include <math.h>
#include <stdio.h>
using namespace std;
bool islegal(string s);
double tran(string s);
int main() {
int n;
cin >> n;
string s;
double res = 0.0;
int num = 0;
for (int i = 0;i<n; ++i) {
cin >> s;
if (islegal(s)) {
double x = tran(s);
if (x >= -1000 && x <= 1000) {
num++;
res += tran(s);
}
else {
cout << "ERROR: " << s << " is not a legal number" << endl;
}
}
else {
cout << "ERROR: "<<s<<" is not a legal number" << endl;
}
}
if (num == 0) {
printf("The average of 0 numbers is Undefined");
}
else if (num == 1) {
printf("The average of 1 number is %.2f", res);
}
else {
printf("The average of %d numbers is %.2f", num , res/num);
}
system("pause");
return 0;
}
double tran(string s) {
double sum = 0;
bool f = 0;
int pos = s.size()-1;
for (int i = 0; i < s.size(); ++i) {
if (s[i] == '-') {
f = 1;
continue;
}
if (s[i] == '.') {
pos = i;
continue;
}
sum *= 10;
sum += (s[i] - '0');
}
if (f) sum = -sum;
sum /= pow(10, s.size()-1 - pos);
return sum;
}
bool islegal(string s) {
int pos = s.size()-1;
int num = 0;
for (int i = 0; i < s.size(); ++i) {
if (s[i] == '.' || s[i] >= '0'&&s[i] <= '9' || s[i] == '-'&&i == 0) {
if (s[i] == '.') {
pos = i;
num++;
}
}
else return 0;
}
if (num > 1) return 0;
if (s.size() - 1 - pos > 2) return 0;
return 1;
}