1:
#include <stdio.h>
int prime(int n) {
    if (n < 2) return(0);
    for (int i = 2; i*i <= n; i++)
        if (n%i == 0) return(0);
    return(1);
}
int main() {
    int n;
    scanf("%d", &n);
    printf("%d\n", prime(n));
    return(0);
}

2:
#include <stdio.h>
void formato_relogio(int total, int* h, int* m, int* s) {
    *h = total / 3600;
    *m = (total % 3600) / 60;
    *s = total % 60;
    printf("%d:%d:%d\n", *h, *m, *s);
}
int main() {
    int total, h, m, s;
    scanf("%d", &total);
    formato_relogio(total, &h, &m, &s);
    return(0);
}


3:
#include <stdio.h>
#include <stdlib.h>
void formato_relogio(int total, int* h, int* m, int* s) {
    *h = total / 3600;
    *m = (total % 3600) / 60;
    *s = total % 60;
    printf("%d:%d:%d\n", *h, *m, *s);
}
int main(int argc, char* argv[]) {
    if (argc < 2) return(1);
    int total = atoi(argv[1]);
    int h, m, s;
    formato_relogio(total, &h, &m, &s);
    return(0);
}

4:
#include <stdio.h>
long long fat_iter(long long n) {
    long long ans = 1;
    for (long long i = 1; i <= n; i++)
        ans *= i;
    return(ans);
}
long long fat_rec(long long n) {
    if (n == 0) return(1);
    return(n * fat_rec(n-1));
}
double pot_iter(double a, int n) {
    double ans = 1.0;
    for (int i = 0; i < n; i++)
        ans *= a;
    return(ans);
}
double pot_rec(double a, int n) {
    if (n == 0) return(1.0);
    return(a * pot_rec(a, n-1));
}
int main() {
    double a;
    int n;
    scanf("%lf %d", &a, &n);
    printf("%lld\n", fat_iter((long long)n));
    printf("%lld\n", fat_rec((long long)n));
    printf("%.2f\n", pot_iter(a, n));
    printf("%.2f\n", pot_rec(a, n));
    return(0);
}


5:
#include <stdio.h>
int mdc(int a, int b) {
    if (b == 0) return(a);
    return(mdc(b, a % b));
}
int main() {
    int n, m;
    scanf("%d %d", &n, &m);
    printf("%d\n", mdc(n, m));
    return(0);
}

6:
#include <stdio.h>
void ord3(int* a, int* b, int* c) {
    int aux;
    if (*a > *b) { aux = *a; *a = *b; *b = aux; }
    if (*b > *c) { aux = *b; *b = *c; *c = aux; }
    if (*a > *b) { aux = *a; *a = *b; *b = aux; }
}
int main() {
    int a, b, c;
    scanf("%d %d %d", &a, &b, &c);
    ord3(&a, &b, &c);
    printf("%d %d %d\n", a, b, c);
    return(0);
}

7:
#include <stdio.h>
int nrecrutados(int nivel) {
    if (nivel == 0) return(1);
    return(3 * nrecrutados(nivel - 1));
}
int main() {
    int nivel;
    scanf("%d", &nivel);
    printf("%d\n", nrecrutados(nivel));
    return(0);
}

8:
#include <stdio.h>
#include <stdlib.h>
void sacar(int valor, int* n200, int* n100, int* n50, int* n20, int* n10, int* n5, int* n2, int* n1) 
    *n200 = valor / 200; valor %= 200;
    *n100 = valor / 100; valor %= 100;
    *n50  = valor / 50;  valor %= 50;
    *n20  = valor / 20;  valor %= 20;
    *n10 = valor / 10;  valor %= 10;
    *n5 = valor / 5;   valor %= 5;
    *n2 = valor / 2;   valor %= 2;
    *n1 = valor;
    printf("200: %d\n", *n200);
    printf("100: %d\n", *n100);
    printf("50: %d\n", *n50);
    printf("20: %d\n", *n20);
    printf("10: %d\n", *n10);
    printf("5: %d\n", *n5);
    printf("2: %d\n", *n2);
    printf("1: %d\n", *n1);
}
int main(int argc, char* argv[]) {
    if (argc < 2) {
        printf("Erro.\n");
        return(1);
    }
    int valor = atoi(argv[1]);
    int n200, n100, n50, n20, n10, n5, n2, n1;
    sacar(valor, &n200, &n100, &n50, &n20, &n10, &n5, &n2, &n1);
    return(0);
}

9:
#include <stdio.h>
void rebalancear(double* preco_petr, double* preco_itub, double aporte) {
    double parte_barata = 0.7 * aporte;
    double parte_cara = 0.3 * aporte;
    if (*preco_petr < *preco_itub) {
        *preco_petr += parte_barata / (*preco_petr);
        *preco_itub += parte_cara / (*preco_itub);
        printf("PETR4 recebeu o maior aporte\n");
    } else {
        *preco_itub += parte_barata / (*preco_itub);
        *preco_petr += parte_cara / (*preco_petr);
        printf("ITUB4 recebeu o maior aporte\n");
    }
}
int main() {
    double preco_petr, preco_itub, aporte;
    scanf("%lf %lf %lf", &preco_petr, &preco_itub, &aporte);
    rebalancear(&preco_petr, &preco_itub, aporte);
    printf("%.2f %.2f\n", preco_petr, preco_itub);
    return(0);
}

10:
#include <stdio.h>
double raiz(double n) {
    double x = n;
    double e = 0.00001;
    while ((x*x - n) > e || (n - x*x) > e) {
        x = (x + n/x) / 2;
    }
    return(x);
}
int main() {
    double n;
    scanf("%lf", &n);
    printf("%.4f\n", raiz(n));
    return(0);
}

(outra solução para 10)
#include <stdio.h>
double raiz(double n) {
    double p = 0.0;
    double q = (n>1.0) ? n: 1.0;
    double m;
    while((q-p)>0.00001) {
        m = (q + p) / 2.0;
        if(m*m > n)
            q = m;
        else
            p = m;
    }
    return(m);
}
int main() {
    double n;
    scanf("%lf", &n);
    printf("%.4f\n", raiz(n));
    return(0);
}