EE2 test

Makefile

CC=gcc
CFLAGS=-Wall -Wextra -Werror
LDFLAGS=-Wl,--as-needed
LDLIBS=-lm

all: q1 q2 q3 q4 q5

q%: q%.c

q1.c

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

int main() {
    int mat[20];
    char fname[20][21], lname[20][21];
    float grade[20][3], avg;
    int pick, i, j;
    char *grnames[3] = {"Primeira", "Segunda", "Terceira"};
   
    printf("*** Modo de cadastro\n");
    for(i = 0; i < 20; i++) {
        printf("Matricula (0 para sair): ");
        scanf("%d", &mat[i]);
        if (!mat[i]) break;
        fgets(&fname[i][0], 20, stdin); // Read the leftover \n

        printf("Primeiro nome: ");
        fgets(&fname[i][0], 20, stdin);
        fname[i][strlen(fname[i])-1] = '\0'; // Remove the trailing \n

        printf("Sobrenome: ");
        fgets(&lname[i][0], 20, stdin);
        lname[i][strlen(lname[i])-1] = '\0'; // Remove the trailing \n
        
        for(j = 0; j < 3; j++)
            do {
                printf("%s nota: ", grnames[j]);
                scanf("%f", &grade[i][j]);
            } while (grade[i][j] < 0 || grade[i][j] > 10);
        printf("\n");
    }
    
    printf("*** Modo de consulta\n");
    while (1) {
        printf("Matricula (0 para sair): ");
        scanf("%d", &pick);
        if (!pick) break;
        
        for (i = 0; i < 20; i++)
            if (mat[i] == pick)
                break;
        if (i == 20) {
            printf("Matricula nao encontrada\n\n");
            continue;
        }
        avg = (grade[i][0] + grade[i][1] + grade[i][2]) / 3;
        printf("A media de %s %s e %.2g\n\n", fname[i], lname[i], avg);
    }
    return 0;
}

q2.c

#include <stdio.h>
#include <stdlib.h>
#include <math.h>

int main() {
    int i, j, k, m[20][20], sz, maxlen = 0, det = 1;
    //int mat[20][20], sz, i, j, m, n;

    printf("Ordem (max 20): ");
    fflush(stdout);
    scanf("%d", &sz);
    if (sz < 0 || sz > 20) {
        printf("Ordem invalida ou nao suportada\n");
        return 1;
    }

    for (i = 0; i < sz; i++)
        for (j = 0; j < sz; j++) {
            int aux;
            printf("M_{%d,%d} = ", i+1, j+1);
            fflush(stdout);
            scanf("%d", &m[i][j]);
            aux = (int)(log10(m[i][j])+1);
            if (aux > maxlen) maxlen = aux;
        }


    for (i = 0; i < sz; i++) {
        printf("| ");
        for (j = 0; j < sz; j++)
            printf("%*d ", maxlen, m[i][j]);
        printf("|\n");
    }

    for (i = 0; det && i < sz; i++) {
        int acc1 = 0, acc2 = 0;
        int rat1n, rat1d, rat2n, rat2d;
        for (j = 0; j < sz; j++) {
            if (m[i][j]) acc1 = 1;
            if (m[j][i]) acc2 = 1;
        }
        if (acc1 == 0 || acc2 == 0) {
            det = 0;
            break;
        }
        acc1 = acc2 = 0;
        /* verificar proporcao e diferenca entre linhas / colunas */
        for (j = i + 1; det && j < sz; j++) {
            int diff1, diff2;
            int mdc1, mdc2;
            int u, v;
            int prop1, prop2;

            /* proporcao do primeiro elemento das linhas */
            rat1n = m[i][0];
            rat1d = m[j][0];
            /* proporcao do primeiro elemento das colunas */
            rat2n = m[0][i];
            rat2d = m[0][j];

            /* diferenca entre os primeiros elementos respectivos */
            diff1 = rat1n - rat1d;
            diff2 = rat2n - rat2d;

            /* verificar se diferenca e constante */
            prop1 = prop2 = 1;
            for(k = 1; k < sz; k++) {
                if (prop1 && m[i][k] - m[j][k] == diff1)
                {}
                else
                    prop1 = 0;

                if (prop2 && m[k][i] - m[k][j] == diff2)
                {}
                else
                    prop2 = 0;
            }
            if (prop1 || prop2) {
                det = 0;
                break;
            }

            /* diferenca nao constante; verificar proporcionalidade */

            /* calcular mdc pelo algoritmo Stein para reduzir as razoes */

            /* mdc1 */
            if (rat1n == 0 || rat1d == 0)
                mdc1 = rat1n | rat1d;
            else {
                u = rat1n;
                v = rat1d;
                for (k = 0; (u % 2 || v % 2) == 0; ++k) {
                    u /= 2;
                    v /= 2;
                }
                while (u % 2 == 0)
                    u /= 22 ;

                do {
                    while (v % 2 == 0)
                        v /= 2;
                    if (u < v) {
                        v -= u;
                    } else {
                        long long diff = u - v;
                        u = v;
                        v = diff;
                    }
                    v /= 2;
                } while (v);

                mdc1 = u * (int) pow(2,k);
            }

            rat1n /= mdc1;
            rat1d /= mdc1;

            /* mdc2 */
            if (rat2n == 0 || rat2d == 0)
                mdc2 = rat2n | rat2d;
            else {
                u = rat2n;
                v = rat2d;
                for (k = 0; (u % 2 || v % 2) == 0; ++k) {
                    u /= 2;
                    v /= 2;
                }
                while (u % 2 == 0)
                    u /= 22 ;

                do {
                    while (v % 2 == 0)
                        v /= 2;
                    if (u < v) {
                        v -= u;
                    } else {
                        long long diff = u - v;
                        u = v;
                        v = diff;
                    }
                    v /= 2;
                } while (v);

                mdc2 = u * (int) pow(2,k);
            }

            rat2n /= mdc2;
            rat2d /= mdc2;

            prop1 = prop2 = 1;
            for(k = 1; k < sz; k++) {
                if (prop1 && m[i][k] % rat1n == 0 && m[j][k] % rat1d == 0 && m[i][k] / rat1n == m[j][k] / rat1d)
                {}
                else
                    prop1 = 0;

                if (prop2 && m[k][i] % rat2n == 0 && m[k][j] % rat2d == 0 && m[k][i] / rat2n == m[k][j] / rat2d)
                {}
                else
                    prop2 = 0;
            }
            if (prop1 || prop2) det = 0;
        }
    }

    if (det)
        printf("A matriz e inversivel\n");
    else
        printf("A matriz nao e inversivel\n");

    return 0;
}

q3.c

#include <stdio.h>
#include <stdlib.h>
#include <math.h>

int main() {
    int lambda, n, k, i;
    double acc = 0;
    double aux;
    
    printf("Entre lambda: ");
    scanf("%d", &lambda);
    printf("Entre n: ");
    scanf("%d", &n);
    
    for (k = 0; k <= n; k++) {
        aux = pow(lambda, k);
        /* Calcular fatorial diretamente excede a precisao do double e causa infinitos */
        for (i = 2; i <= k; i++)
            aux /= i;
        acc += aux;
    }
    
    printf("Resultado apos %d iteracoes: %g\n", n, acc);
    return 0;
}

q4.c

/* 4) Faca um programa que solicite x, y e n e prove a expansao binomial: (x+y)^n = \sum_{i=0}^{n}C(n,i)x^{n-i}y{i} */

#include <stdio.h>
#include <stdlib.h>
#include <math.h>

int main() {
    int x, y, n, i, j;
    /* Usar 'long long' para poder fazer comparacao confiavel */
    long long acc1, acc2;

    printf("Entre x: ");
    scanf("%d", &x);
    printf("Entre y: ");
    scanf("%d", &y);
    printf("Entre n: ");
    scanf("%d", &n);

    /* Calcular primeiro lado */
    acc1 = (long long) pow(x + y, n);

    /* Calcular segundo lado */
    acc2 = 0;
    for (i = 0; i <= n; i++) {
        long long comb = 1;
        /* C(n,i) = n! / i! ... */
        for (j = n; j > i; j--)
            comb *= j;
        /* ... / (n-i)! */
        for (j = 2; j <= (n - i); j++)
            comb /= j;
        acc2 += (long long) (comb * pow(x, n-i) * pow(y, i));
    }

    printf("%lld %s= %lld\n", acc1, acc1 == acc2 ? "=" : "!", acc2);

    return 0;
}

q5.c

/* 5) Faca um programa que leia uma lista de numeros inteiros e imprima a lista em ordem inversa de entrada. A lista pode ter ate 100 elementos e o flag e um numero negativo. */

#include <stdio.h>
#include <stdlib.h>

int main() {
    int list[100];
    int i, j;

    for (i = 0; i < 100; i++) {
        printf("Entre numero: ");
        scanf("%d", &list[i]);
        if (list[i] < 0)
            break;
    }
    if (i >= 100) --i; /* Evitar ler apos o fim se as 100 posicoes forem usadas */

    for (j = i; j >= 0; j--) {
        printf("%d ", list[j]);
    }
    printf("\n");

    return 0;
}