Bài tập C có lời giải

/**
 * Tinh day so Fibonacci KHONG dung phuong phap de quy
 *  
 * @author viettuts.vn
 */

 #include<stdio.h>

/**
 * Tinh so Fibonacci thu n
 * 
 * @param n: chi so cua so Fibonacci tinh tu 0 
 *           vd: F0 = 0, F1 = 1, F2 = 1, F3 = 2
 * @return So Fibonacci thu n
 */
int fibonacci(int n) {
    int f0 = 0;
    int f1 = 1;
    int fn = 1;
    int i;

    if (n < 0) {
        return -1;
    } else if (n == 0 || n == 1) {
        return n;
    } else {
        for (i = 2; i < n; i++) {
            f0 = f1;
            f1 = fn;
            fn = f0 + f1;
        }
    }
    return fn;
}

/**
 * Ham main
 */
int main() {
 int i;
    printf("10 so dau tien cua day so Fibonacci: \n");
    for (i = 0; i < 10; i++) {
        printf("%d ", fibonacci(i));
    }
}

#include<stdio.h>
 
/**
 * check so nguyen to trong C
 * 
 * @author viettuts.vn
 * @param n: so nguyen duong
 * @return 1 la so nguyen so, 
 *         0 khong la so nguyen to
 */
int isPrimeNumber(int n) {
    // so nguyen n < 2 khong phai la so nguyen to
    if (n < 2) {
        return 0;
    }
    // check so nguyen to khi n >= 2
    int squareRoot = (int) sqrt(n);
    int i;
    for (i = 2; i <= squareRoot; i++) {
        if (n % i == 0) {
            return 0;
        }
    }
    return 1;
}

/**
 * Ham main
 */
int main() {
 int i;
    printf("Cac so nguyen to nho hon 100 la: \n");
    for (i = 0; i < 100; i++) {
        if (isPrimeNumber(i)) {
            printf("%d ", i);
        }
    }
}

/**
 * Tinh giai thua KHONG dung phuong phap de quy
 *  
 * @author viettuts.vn
 */

#include<stdio.h>

/**
 * tinh giai thua
 * 
 * @author viettuts.vn
 * @param n: so nguyen duong
 * @return giai thua cua so n
 */
long tinhGiaithua(int n) {
 int i;
    long giai_thua = 1;
    if (n == 0 || n == 1) {
        return giai_thua;
    } else {
        for (i = 2; i <= n; i++) {
            giai_thua *= i;
        }
        return giai_thua;
    }
}

/**
 * Ham main
 */
int main() {
    int a = 5;
    int b = 0;
    int c = 10;
    printf("Giai thua cua %d  la: %d \n",  a, tinhGiaithua(a));
    printf("Giai thua cua %d  la: %d \n",  b, tinhGiaithua(b));
    printf("Giai thua cua %d  la: %d",  c, tinhGiaithua(c));
}

/**
 * Chuong trinh chuyen doi he co so trong C
 * Bai tap nay su dung bang ASCII de chuyen doi so nguyen thanh kieu ky tu
 * Link tham khao: https://vi.wikipedia.org/wiki/ASCII
 *  
 * @author viettuts.vn
 */

#include<stdio.h>

const char CHAR_55 = 55;
const char CHAR_48 = 48;

/**
 * chuyen doi so nguyen n sang he co so b
 * 
 * @author viettuts.vn
 * @param n: so nguyen
 * @param b: he co so
 */
int convertNumber(int n, int b) {
    if (n < 0 || b < 2 || b > 16 ) {
        printf("He co so hoac gia tri chuyen doi khong hop le!");
        return 0;
    }
    int i;
    char arr[20];
    int count = 0;
    int m;
    int remainder = n;
    while (remainder > 0) {
        if (b > 10) {
            m = remainder % b;
            if (m >= 10) {
                arr[count] = (char) (m + CHAR_55);
                count++;
            } else {
                arr[count] = (char) (m + CHAR_48);
                count++;
            }
        } else {
            arr[count] = (char) ((remainder % b) + CHAR_48);
            count++;
        }
        remainder = remainder / b;
    }
    // hien thi he co so
    for (i = count - 1; i >= 0; i--) {
        printf("%c", arr[i]);
    }
    return 1;
}

/**
 * Ham main
 */
int main() {
    int n = 12;
    printf("So %d trong he co so 2 = ", n);
    convertNumber(n, 2);
    printf("\nSo %d trong he co so 16 = ", n);
 convertNumber(n, 16);
    return 1;
}

#include <stdio.h>
 
/**
 * giai phuong trinh bac 2: ax2 + bx + c = 0
 * 
 * @param a: he so bac 2
 * @param b: he so bac 1
 * @param c: so hang tu do
 */
void giaiPTBac2(float a, float b, float c) {
    // kiem tra cac he so
    if (a == 0) {
        if (b == 0) {
            printf("Phuong trinh vo nghiem!");
        } else {
            printf("Phuong trinh co mot nghiem: x = %f", (-c / b));
        }
        return;
    }
    // tinh delta
    float delta = b*b - 4*a*c;
    float x1;
    float x2;
    // tinh nghiem
    if (delta > 0) {
        x1 = (float) ((-b + sqrt(delta)) / (2*a));
        x2 = (float) ((-b - sqrt(delta)) / (2*a));
        printf("Phuong trinh co 2 nghiem la: x1 = %f va x2 = %f", x1, x2);
    } else if (delta == 0) {
        x1 = (-b / (2 * a));
        printf("Phong trinh co nghiem kep: x1 = x2 = %f", x1);
    } else {
        printf("Phuong trinh vo nghiem!");
    }
}

/**
 * ham main
 */
int main() {
 float a, b, c;
    printf("Nhap he so bac 2, a = ");
    scanf("%f", &a);
    printf("Nhap he so bac 1, b = ");
    scanf("%f", &b);
    printf("Nhap so hang tu do, c = ");
    scanf("%f", &c);
    giaiPTBac2(a, b, c);
    return 1;
}

/**
 * Chuong trinh tim uoc chung lon nhat (USCLN)
 * va boi so chung nho nhat (BSCNN) cua 2 so a và b
 * 
 * @author viettuts.vn
 */
#include<stdio.h>

/**
 * Tim uoc so chung lon nhat (USCLN)
 */
int USCLN(int a, int b) {
    if (b == 0) return a;
    return USCLN(b, a % b);
}

/**
 * Tim boi so chung nho nhat (BSCNN)
 */
int BSCNN(int a, int b) {
    return (a * b) / USCLN(a, b);
}

/**
 * Ham main
 */
int main() {
 int a, b;
    printf("Nhap so nguyen duong a = ");
    scanf("%d", &a);
    printf("Nhap so nguyen duong b = ");
    scanf("%d", &b);
    // tinh USCLN cua a và b
    printf("USCLN cua %d va %d la: %d", a, b, USCLN(a, b));
    // tinh BSCNN cua a và b
    printf("USCLN cua %d va %d la: %d", a, b, BSCNN(a, b));
}

/**
 * Chuong liet ke cac so nguyen to nho hon n.
 * 
 * @author viettuts.vn
 */
#include<stdio.h>

/**
 * check so nguyen to
 * 
 * @author viettuts.vn
 * @param n: so nguyen duong
 * @return 1: la so nguyen so, 
 *         0: khong la so nguyen to
 */
int isPrimeNumber(int n) {
    // so nguyen n < 2 khong phai la so nguyen to
    if (n < 2) {
        return 0;
    }
    // check so nguyen to khi n >= 2
    int i;
    int squareRoot = (int) sqrt(n);
    for (i = 2; i <= squareRoot; i++) {
        if (n % i == 0) {
            return 0;
        }
    }
    return 1;
}

/**
 * Ham main
 */
int main() {
 int i, n;
    printf("Nhap n = ");
    scanf("%d", &n);
    printf("Tat ca cac so nguyen to nho hon %d la: \n", n);
    if (n >= 2) {
        printf("%d ", 2);
    }
    for (i = 3; i < n; i+=2) {
        if (isPrimeNumber(i) == 1) {
            printf("%d ", i);
        }
    }
}

/**
 * Chuong trinh liet ke n so nguyen to dau tien.
 * 
 * @author viettuts.vn
 */
 #include<stdio.h>
 #include<math.h>

/**
 * check so nguyen to
 * 
 * @author viettuts.vn
 * @param n: so nguyen duong
 * @return 1: la so nguyen so, 
 *         0: khong la so nguyen to
 */
int isPrimeNumber(int n) {
    // so nguyen n < 2 khong phai la so nguyen to
    if (n < 2) {
        return 0;
    }
    // check so nguyen to khi n >= 2
    int i;
    int squareRoot = sqrt(n);
    for (i = 2; i <= squareRoot; i++) {
        if (n % i == 0) {
            return 0;
        }
    }
    return 1;
}

/**
 * Ham main
 */
int main() {
 int n;
    printf("Nhap n = ");
    scanf("%d", &n);
    printf("%d so nguyen to dau tien la: \n", n);
    int dem = 0; // dem tong so nguyen to
    int i = 2;   // tim so nguyen to bat dau tu so 2
    while (dem < n) {
        if (isPrimeNumber(i)) {
            printf("%d ", i);
            dem++;
        }
        i++;
    }
}

/**
 * Chuong trinh liet ke tat ca so nguyen to co 5 chu so.
 * 
 * @author viettuts.vn
 */
 
#include<stdio.h>

/**
 * check so nguyen to
 * 
 * @author viettuts.vn
 * @param n: so nguyen duong
 * @return 1: la so nguyen so, 
 *         0: khong la so nguyen to
 */
int isPrimeNumber(int n) {
    // so nguyen n < 2 khong phai la so nguyen to
    if (n < 2) {
        return 0;
    }
    // check so nguyen to khi n >= 2
    int i;
    int squareRoot = (int) sqrt(n);
    for (i = 2; i <= squareRoot; i++) {
        if (n % i == 0) {
            return 0;
        }
    }
    return 1;
}

/**
 * Ham main
 */
int main() {
    int count = 0;
    int i;
    printf("Liet ke tat ca cac so co 5 chu so:");
    for (i = 10001; i < 99999; i+=2) {
        if (isPrimeNumber(i)) {
            printf("%d\n", i);
            count++;
        }
    }
    printf("Tong cac so nguyen to co 5 chu so la: %d", count);
}

/**
 * Chuong trinh phan tich so nguyen n thanh tich cac thua so nguyen to
 * Vi du: 12 = 2 x 2 x 3.
 * 
 * @author viettuts.vn
 */
#include<stdio.h>

/**
 * Phan tich so nguyen n thanh tich cac thua so nguyen to
 */
void phanTichSoNguyen(int n) {
    int i = 2;
    int dem = 0;
    int a[100];
    // phan tich
    while (n > 1) {
        if (n % i == 0) {
            n = n / i;
            a[dem++] = i;
        } else {
            i++;
        }
    }
    // neu dem = 0 thi n la nguyen to
    if (dem == 0) {
        a[dem++] = n;
    }
    // in ket qua ra man hinh
    for (i = 0; i < dem - 1; i++) {
        printf("%d x ", a[i]);
    }
    printf("%d", a[dem - 1]);
}

/**
 * Ham main
 */
int main() {
 int n;
    printf("Nhap so nguyen duong n = ");
    scanf("%d", &n);
    // phan tich so nguyen duong n
    phanTichSoNguyen(n);
}

#include<stdio.h>
 
const int DEC_10 = 10;

/**
 * Ham main
 */
int main() {
 int n;
    printf("Nhap so nguyen duong n = ");
    scanf("%d", &n);
    printf("Tong cac chu so cua %d la: %d", n, totalDigitsOfNumber(n));
}

/**
 * Tinh tong cac chu so cua mot so nguyen duong
 */
int totalDigitsOfNumber(int n) {
    int total = 0;
    do {
        total = total + n % DEC_10;
        n = n / DEC_10;
    } while (n > 0);
    return total;
}

/**
 * Chuong trình li?t kê t?t c? các s? thu?n ngh?ch có 6 ch?a s?.
 * 
 * @author viettuts.vn
 */
 #include<stdio.h>
    
const int DEC_10 = 10;

/**
 * main
 * 
 * @param args
 */
int main() {
    int count = 0, i;
    // in ra man hinh cac so thuan nghich co 6 chu so
    for (i = 100000; i < 1000000; i++) {
        if (isThuanNghich(i)) {
            printf("%d\n", i);
            count++;
        }
    }
    printf("Tong cac so thuan nghich co 6 chu so la: %d", count);
}

/**
 * kiem tra so thuan nghich
 * 
 * @param n: so nguyen duong
 * @return 1: la so thuan nghich
 *         0: khong la so thuan nghich
 */
int isThuanNghich(int n) {
    int a[20];
    int dem = 0, i;
    // phan tich n thanh mang cac chu so
    do {
        a[dem++] = (n % DEC_10);
        n = n / DEC_10;
    } while (n > 0);
    // kiem tra tinh thuan nghich
    for (i = 0; i < (dem/2); i++) {
        if (a[i] != a[(dem - i - 1)]) {
            return 0;
        }
    }
    return 1;
}

/**
 *  Chuong trinh liet ke cac so Fibonacci nho hon n la so nguyen to.
 *  
 * @author viettuts.vn
 */
#include<stdio.h>

/**
 * Ham main
 */
int main() {
 int n;
    printf("Nhap so nguyen duong = ");
    scanf("%d", &n);
    printf("Cac so fibonacci nho hon %d va la so nguyen to: ", n);
    int i = 0;
    while (fibonacci(i) < n) {
        int fi = fibonacci(i);
        if (isPrimeNumber(fi)) {
            printf("%d ", fi);
        }
        i++;
    }
}

/**
 * Tinh so fibonacci thu n
 * 
 * @param n: chi so cua day fibonacci tinh tu 0
 *           vd: F0 = 0, F1 = 1, F2 = 1, F3 = 2
 * @return so fibonacci thu n
 */
int fibonacci(int n) {
    if (n < 0) {
        return -1;
    } else if (n == 0 || n == 1) {
        return n;
    } else {
        return fibonacci(n - 1) + fibonacci(n - 2);
    }
}

/**
 * check so nguyen to
 * 
 * @author viettuts.vn
 * @param n: so nguyen duong
 * @return 1: la so nguyen so, 
 *         0: khong la so nguyen to
 */
int isPrimeNumber(int n) {
    // so nguyen n < 2 khong phai la so nguyen to
    if (n < 2) {
        return 0;
    }
    // check so nguyen to khi n >= 2
    int i;
    int squareRoot = sqrt(n);
    for (i = 2; i <= squareRoot; i++) {
        if (n % i == 0) {
            return 0;
        }
    }
    return 1;
}