题解 | #跳台阶#

#include <stdio.h>

int jump_step(int a) {
	int i, b, c, d;
	if (a == 1) 
		return 1;
	if (a == 2) 
		return 2;
	b = 1; // -2
	c = 2; // -1
	for (i = 2; i < a; i++) {
		d = b + c;
		b = c;
		c = d;
	}
	return d;
}

int main(int argc, char *argv[]) {
	int num;
	while (scanf("%d", &num) == EOF || num < 1 || num > 40) {
		printf("input error, please input again\n");
	}
	printf("%d\n", jump_step(num));
	return 0;
}