BÀI 12

BÀI 12: viết chương trình tìm số Fibonacci thứ n.

CODE 1:

#include<stdio.h>
#include<conio.h>

long fibonaci(int);
int main()
{

    int n;
    printf("Nhap n=");
    scanf("%d",&n);
    printf("\n%ld",fibonaci(n));
    getch();
    return 0;
}
long fibonaci(int n)
{
    return (n==0||n==1)?1:fibonaci(n-1)+fibonaci(n-2);
}




CODE 2:

// cau 17:viet ham tra ve so fibonacy thu n
#include<stdio.h>
#include<conio.h>
unsigned long int fib(int n)
{
	int i;
	if(n==1||n==2)
		return 1;
	else
		return (fib(n-1)+fib(n-2));
}
// ham chinh:
void main()
{
	int n;
	clrscr();
	vao:
	printf("\n Nhap vao:n=");
	scanf("%d",&n);
	if(n<=0)
	{
		printf("\n Ban nhap sai gia tri cua n.Vui long nhap lai");
		getch(); goto vao;
	}
	else
		printf("\n So fibonacy %d la:%u",n,fib(n));
	getch();
}






CODE 3: (CODE TEST TỐT)

#include <stdio.h>
#include <conio.h>

void tinhheso(long* a11, long* a12, long* a21, long* a22, int n)
{
    long _a11, _a12, _a21, _a22;
    long x11, x12 ,x21, x22;
    if(n == 1){
        *a11 = 0;
        *a12 = *a21 = *a22 = 1;
        return ;
    }
    if(n == 2){
        *a11 = *a12 = *a21 = 1;
        *a22 =2;
        return ;
    }
    tinhheso(&_a11,&_a12,&_a21,&_a22,n/2);
    *a11 = _a11*_a11 + _a12*_a21;
    *a12 = _a11*_a12 + _a12*_a22;
    *a21 = _a21*_a11 + _a22*_a21;
    *a22 = _a21*_a12 + _a22*_a22;
    if(n%2 == 0) return ;
    else{
        /*Tinh he so ma tran A^(n/2) * A^(n/2)*/
        x11 = *a11;
        x12 = *a12;
        x21 = *a21;
        x22 = *a22;

        /*Tinh he so ma tran A^n*/
        *a11 = x12;
        *a12 = x11 + x12;
        *a21 = x22;
        *a22 = x21 + x22;
    }
}

int main()
{
    int n;
    long a11, a12, a21, a22;
    do{
    printf("Nhap n: ");
    scanf("%d", &n);
    if(n == 0) {
        printf("F(0) = 1\n");
        continue;
    }
    tinhheso(&a11, &a12, &a21, &a22, n);
    printf("F(%d) = %ld\n", n, a11 + a21);
    }while(getch()!=27);
    return 0;
}