HDU 4493 Tutor （控制精度）

#include <cstdio>
#include <string>
#include <cstdlib>
#include <cmath>
#include <iostream>
#include <cstring>
#include <set>
#include <queue>
#include <algorithm>
#include <vector>
#include <map>
#include <cctype>
using namespace std ;
typedef long long LL;
typedef pair<int, int> P;
const int INF = 0x3f3f3f3f;
const double inf = 0x3f3f3f3f3f3f3f;
const double eps = 1e-8;
const int maxn = 2e5 + 5;
const int dr[] = {0, 0, -1, 1};
const int dc[] = {-1, 1, 0, 0};
int n, m;
inline bool is_in(int r, int c){
    return r >= 0 && r < n && c >= 0 && c < m;
}
int a[maxn];

int main(){
    int T;  cin >> T;
    while(T--){
        double sum = 0;
        double x;
        for(int i = 0; i < 12; ++i){
            cin >> x;
            sum += x;
        }
        int ans = (int)round(sum * 100.0/12.0);
        printf("$");
        printf("%d", ans/100);
        int y = ans % 100;
        if(!y);
        else{
            printf(".%d", y /10);
            y = y % 10;
            if(!y) ;
            else  printf("%d", y %10);
        }
        printf("\n");
    }
    return 0;
}