1108 Finding Average (20 分)
阿新 • • 發佈:2018-12-08
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
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
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
真沒注意那個單數的時候,以為是一句廢話,沒看見單複數。
#include<bits/stdc++.h>
using namespace std;
typedef long long LL;
#define rep(i,a,b) for(int i=a;i<b;++i)
const double eps=1e-5;
const int N=110;
char str[N][N];
double get(int x,int pos){
int len=x-pos;
double res=1;
for(int i=1;i<=len;i++)res*=0.1;
return res;
}
/*
3
-0.1 -2.3- 2.01
1
-999.99
*/
int ok(int x,double& res){
res=0;
int len=strlen(str[x]);
int num_pot=0,num_fu=0;
rep(i,0,len){
if(str[x][i]=='.')num_pot++;
if(str[x][i]=='-')num_fu++;
if(!(str[x][i]>='0'&&str[x][i]<='9'||str[x][i]=='.'||str[x][i]=='-'))return 0;
}
if(num_pot>1||num_fu>1)return 0;
if(num_fu==1&&str[x][0]!='-')return 0;
if(num_pot){
int pos=0;
for(int i=0;i<len;i++){
if(str[x][i]=='.'){
pos=i;break;
}
}
//printf("len:%d pos:%d\n",len,pos);
if(len-pos>3) return 0;
int i=0;
if(str[x][0]=='-')i++;
for(;i<pos;i++){
res=res*10.0+str[x][i]-'0';
}
double res2=0;
for(i=pos+1;i<len;i++){
res2+=get(i,pos)*(str[x][i]-'0');
}
res+=res2;
if(str[x][0]=='-')res*=-1;
}else{
int i=0;
if(str[x][0]=='-')i++;
for(;i<len;i++){
res=res*10+str[x][i]-'0';
}
if(str[x][0]=='-')res*=-1;
}
return 1;
}
int main(){
int n;
scanf("%d",&n);
rep(i,0,n)scanf(" %s",str[i]);
int cnt=0;double sum=0;
int p=0;
rep(i,0,n){
double res=-2000;
if(ok(i,res)&&res<=1000&&res>=-1000){
//printf("i:%d %.2f\n",i,res);
p=i;
cnt++;
sum+=res;
}else{
printf("ERROR: %s is not a legal number\n",str[i]);
}
}
// printf("sum:%.2f cnt:%d\n",sum,cnt);
if(cnt==0)printf("The average of 0 numbers is Undefined\n");
else if(cnt==1)printf("The average of 1 number is %.2f\n",sum);
else printf("The average of %d numbers is %.2f\n",cnt,sum/cnt);
return 0;
}