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 legalinput 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
字符串转double有多种方法:
double d = (double)strtod(s.c_str(),NULL);
sscanf(s.c_str(),"%lf",&d);
stringstream st(s); st >> d;
#include<stdio.h>
#include<vector>
#include<string>
#include<sstream>
#include<algorithm>
using namespace std;
vector<double> leg;
double str2double(string s){
double d;
stringstream st(s);
st>>d;
return d;
}
int main(){
int n;
scanf("%d",&n);
char c[1000];
for(int i=0;i<n;i++){
scanf("%s",c);
string s(c);
int dot=-1;bool ok=true;
for(int i=0;i<s.size();i++){
if((s[i]>'9'||s[i]<'0')){
if(s[i]=='.'){
if(dot>0||i==0){
ok=false;
break;
}
dot=i;
}else if(i==0&&s[i]=='-'){
continue;
}else{
ok=false;
break;
}
}
}
if(dot>0&&s.size()-1-dot>2)
ok=false;
double d=str2double(s);
if(d>1000||d<-1000)
ok=false;
if(ok){
leg.push_back(d);
}else{
printf("ERROR: %s is not a legal number\n",s.c_str());
}
}
double sum=0.0;
for(int i=0;i<leg.size();i++){
sum+=leg[i];
}
if(leg.size()==0)
printf("The average of 0 numbers is Undefined");
else if(leg.size()>1)
printf("The average of %d numbers is %.2f",leg.size(),sum/leg.size());
else
printf("The average of 1 number is %.2f",leg.size(),sum);
return 0;
}