PATA1108题解

排除含有字母、出现一个小数点又有其他非数字字符、小数点后位数超过两位，数的范围在[-1000,1000]之外的情况即可。

//
//  main.cpp
//  PATA1108
//
//  Created by Phoenix on 2018/2/23.
//  Copyright © 2018年 Phoenix. All rights reserved.
//

#include <iostream>
#include <cstdio>
#include <cstring>


int main(int argc, const char * argv[]) {
    int n, m = 0;
    double ans = 0;
    scanf("%d ", &n);
    for(int i = 0; i < n; i++) {
        int j = 0, num1 = 0, num2 = 0, t = 0, a = 0;
        char s[100];
        scanf("%s", s);
        //printf("%s\n", s);
        bool flag = true;
        int len = strlen(s);
        if(s[0] == '-') {
            j++;
            a = 1;
        }
        while (j < len) {
            while (s[j] >= '0' && s[j] <= '9') {
                j++;
                num1++;
            }
            if(s[j] == '.') {
                num1++;
                t = j + 1;
                j++;
                while (j < len) {
                    if(s[j] >= '0' && s[j] <= '9') {
                        num2++;
                    }
                    j++;
                }
            }
            break;
        }
        //printf("%d %d %d %d\n", a, num1, num2, t);
        if(a + num1 + num2 != len) flag = false;
        else if(t != 0 && (num2 > 2 || len - t != num2)) flag = false;
        else {
            double sum = 0;
            for(int j = 0; j < len; j++) {
                if(s[j] >= '0' && s[j] <= '9') {
                    sum = sum * 10 + s[j] - '0';
                }
            }
            for(int j = 0; j < num2; j++) sum /= 10;
            if(s[0] == '-') sum *= -1;
            if(sum >= -1000 && sum <= 1000) {
                ans += sum;
                m++;
            }else {
                flag = false;
            }
        }
        if(flag == false) printf("ERROR: %s is not a legal number\n", s);
    }
    if(m == 0) printf("The average of 0 numbers is Undefined\n");
    else if(m == 1) printf("The average of 1 number is %.2f\n", ans);
    else printf("The average of %d numbers is %.2f\n", m, ans / m);
    return 0;
}