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[c]代码库

#include <stdio.h>
#define TARGET 40

int getjc(int i) {
	if (i==1) return 1;
	else return i*getjc(i-1);
}

int fib_1(int a) {
	int x,y=1,s=1;
	if (a==0) return 0;
	for (;a>2;a--) {
		x=y;
		y=s;
		s=x+y;
	}
	return s;
}

int fib_2(int a) {
	if (a==1) return 1;
	if (a==0) return 0;
	return fib_2(a-1)+fib_2(a-2);
}

int addorder(int n,int x,int y) {
	if (n==0) return x;
	if (n==1) return y;
	else return addorder(--n,y,x+y);
}

int fib_3(int a) {
	if (a<2) return a;
	return addorder(a,0,1);
}

int main() {
	printf("%d\n",fib_1(TARGET));
	printf("%d\n",fib_2(TARGET));
	printf("%d\n",fib_3(TARGET));
	return 0;
}