C++ 统计疾病患病率与年龄段关系

#include <iostream>
#include <iomanip>
#include <vector>

using namespace std;

int main() {
    int n;
    cin >> n;
    
    vector<int> ages(n);
    for (int i = 0; i < n; i++) {
        cin >> ages[i];
    }
    
    int count1 = 0, count2 = 0, count3 = 0, count4 = 0;
    for (int i = 0; i < n; i++) {
        if (ages[i] >= 0 && ages[i] <= 18) {
            count1++;
        } else if (ages[i] >= 19 && ages[i] <= 35) {
            count2++;
        } else if (ages[i] >= 36 && ages[i] <= 60) {
            count3++;
        } else {
            count4++;
        }
    }
    
    double ratio1 = (double)count1 / n * 100;
    double ratio2 = (double)count2 / n * 100;
    double ratio3 = (double)count3 / n * 100;
    double ratio4 = (double)count4 / n * 100;
    
    cout << fixed << setprecision(2) << ratio1 << '%' << endl;
    cout << fixed << setprecision(2) << ratio2 << '%' << endl;
    cout << fixed << setprecision(2) << ratio3 << '%' << endl;
    cout << fixed << setprecision(2) << ratio4 << '%' << endl;
    
    return 0;
}