1108. Finding Average

1108. Finding Average (20)

时间限制

400 ms

内存限制

65536 kB

代码长度限制

16000 B

判题程序

Standard

作者

CHEN, Yue

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:

75 -3.2 aaa 9999 2.3.4 7.123 2.35

Sample Output 1:

ERROR: aaa is not a legal numberERROR: 9999 is not a legal numberERROR: 2.3.4 is not a legal numberERROR: 7.123 is not a legal numberThe average of 3 numbers is 1.38

Sample Input 2:

2aaa -9999

Sample Output 2:

ERROR: aaa is not a legal numberERROR: -9999 is not a legal numberThe average of 0 numbers is Undefined

这题别想太多，判断下第一个符号‘-’和中间的‘.’，想多容易出错，各种不规范的输入如1. 001等都是合法的。

#include<iostream>#include<string>#include<vector>#include<algorithm>using namespace std;double sum=0;int cnt=0;double s2d(string s){int k=0;double d1=0,d2=0;double d=0;bool f=true;if(s.empty())return 0;if(s[0]=='-')k++;else if(s[0]>='0'&&s[0]<='9');else{cout<<"ERROR: "<<s<<" is not a legal number"<<endl;return 0;}int pos=s.find('.');if(pos!=string::npos){//cout<<"---"<<endl;for(int i=k;i<pos;i++){if(s[i]>='0'&&s[i]<='9')d1=d1*10+s[i]-'0';else{f=false;break;}}if(s.size()-pos<4){for(int i=s.size()-1;i>pos;i--){if(s[i]>='0'&&s[i]<='9')d2=d2/10+s[i]-'0';else{f=false;break;}}d2=d2/10;}elsef=false;}else{for(int i=k;i<s.size();i++){if(s[i]>='0'&&s[i]<='9')d1=d1*10+s[i]-'0';else{f=false;break;}}}d=d1+d2;if(abs(d1+d2)>1000)f=false;if(f==false){cout<<"ERROR: "<<s<<" is not a legal number"<<endl;return 0;}else{cnt++;return k==0?(d1+d2):(-d1-d2);}}int main(){int n;cin>>n;for(int i=0;i<n;i++){string s;cin>>s;sum+=s2d(s);}if(cnt==0)cout<<"The average of 0 numbers is Undefined"<<endl;else if(cnt==1)printf("The average of %d number is %.2lf\n",cnt,sum/cnt);elseprintf("The average of %d numbers is %.2lf\n",cnt,sum/cnt);return 0;}