为什么6 8 11 13 测试点没通过啊

#include<cstdio>
#include <cmath>
using namespace std;
#define PI 3.141593
int tao(int day){
    int tao_zi;
    if(day == 4){
        return 1;
    }
    tao_zi = (tao(day+1)+1)*2;
    return tao_zi;
}
int main() {
    int T; //选择题目
    scanf("%d",&T);
    if (T == 1) {
        printf("I love Luogu!");
    } else if (T == 2) {
        printf("%d %d",2+4,10-2-4);
    } else if (T == 3) {
        int a = 14/4;
        int b = a*4;
        int c = 14%4;
        printf("%d\n%d\n%d",a,b,c);
    } else if (T == 4) {
        float a = 500;
        float b = a/3;
        printf("%.3f",b);
    } else if (T == 5) {
        int a = 260;
        int v_a = 12;
        int b = 220;
        int v_b = 20;
        int t = (a+b)/(v_a+v_b);
        printf("%d",t);
    } else if (T == 6) {
        printf("%f", sqrt(6*6+9*9));
    } else if (T == 7) {
        int a = 100+10;
        int b = a-20;
        int c = 0;
        printf("%d\n%d\n%d",a,b,c);
    } else if (T == 8) {
        double a,s,v;
        a = 2*PI*5;
        s = PI*5*5;
        v = PI*5*5*5*4/3;
        printf("%lf\n%lf\n%lf",a,s,v);
    } else if (T == 9) {
        int sum = tao(1);
        printf("%d",sum);
    } else if (T == 10) {
        printf("%d",9);
    } else if (T == 11) {
        double a=100;
        double t=a/3;
        printf("%lf",t);
    } else if (T == 12) {
        char c[27]={' ','A','B','C','D','E','F','G','H','I','J','K','L','M','N','O','P','Q','R','S',
                    'T','U','V','W','X','Y','Z'};
        for (int i = 0; i < 27; ++i) {
            if('M' == c[i]){
                printf("%d\n",i);
                break;
            }
        }
        printf("%c",c[18]);
    } else if (T == 13) {
        double v1 = PI*4*4*4*4/3;
        double v2 = PI*10*10*10*4/3;
        double v = v1+v2;
        double a = pow(v,1.0/3);
        printf("%lf",a);
    } else if (T == 14) {
        int a=1;//定价
        int b=119; //报名人数
        int sum = 0; //收到的报名费
        while (a>0){
            sum = a*b;
            if(sum == 3500){
                printf("%d",a);
                break;
            }
            a++;
            b--;
        }
    }
    return 0;
}