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 Xis 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
神坑，没有仔细读题，当只有一个合法数时，printf的不是numbers，而是number，所以，务必分类输出！！
法一：
#include<iostream>
#include<cmath>
#include<algorithm>
#include<cctype>
#include<cstring>
#include<cstdlib>
using namespace std;
bool is_legal(char c[100]){
double num = atof(c);
if(num > 1000.0 || num < -1000.0){
return false;
}
char b[100];
sprintf(b, "%.2lf", num);
for(int i = 0; i < strlen(c) ; i++){
if(c[i] != b[i]){
return false;
}
}
return true;
}
int main(){
int n;
cin >> n;
double num_sun = 0;
int cnt = 0;
for(int i = 0; i < n; i++){
char c[100];
cin >> c;
if(is_legal(c)){
double num = atof(c);
cnt++;
num_sun += num;
}else
{
printf("ERROR: %s is not a legal number\n", c);
}
}
if(cnt == 1){
printf("The average of 1 number is %.2f\n", num_sun);
}else if(cnt > 1)
{
printf("The average of %d numbers is %.2lf\n", cnt, num_sun * 1.0 / cnt);
}else
{
printf("The average of 0 numbers is Undefined\n");
}
return 0;
}法二：
#include<iostream>
#include<cmath>
#include<algorithm>
#include<cctype>
#include<cstring>
#include<cstdlib>
using namespace std;
bool is_legal(string s){
int cnt = 0;
for(int i = 0; i < s.length(); i++){
if(((s[i] < '0' || s[i] > '9') && s[i] != '-' && s[i] != '.')){
return false;
}
if((s[i] == '-' && i != 0)){
return false;
}
if(s[i] == '.'){
cnt++;
}
}
if(cnt > 1){
return false;
}else if(stod(s) > 1000.0 || stod(s) < -1000.0)
{
return false;
}
if(cnt == 1){
if((s.length() - s.find('.')) > 3)
return false;
}
return true;
}
int main(){
int n;
cin >> n;
double num_sun = 0;
int cnt = 0;
for(int i = 0; i < n; i++){
string s;
cin >> s;
if(is_legal(s)){
double num = stod(s);
cnt++;
num_sun += num;
}else
{
printf("ERROR: %s is not a legal number\n", s.c_str());
}
}
if(cnt == 1){
printf("The average of 1 number is %.2f\n", num_sun);
}else if(cnt > 1)
{
printf("The average of %d numbers is %.2lf\n", cnt, num_sun * 1.0 / cnt);
}else
{
printf("The average of 0 numbers is Undefined\n");
}
return 0;
}