Somethings about Floors题解

#include <stdio.h>
int main() {
    int f0, f1, a;
    int b, n, i;
    scanf("%d", &n);
    n = n % 21;
    if (n == 0 || n == 1) {
        printf("%d\n", 1);
        return 0;
    }
    f0 = 1;
    f1 = 2;
    for (i = 3; i <= n; i++) {
        a = f0 + f1;
        f0 = f1;
        f1 = a;
    }
    printf("%d\n", f1);
    return 0;
}

// from younglee
// solve the problem in two different way, with recursion and no recursion.
#include<stdio.h>
#include<string.h>
#define N 100
 
#define RECUR 1
#define MODE 0
 
int dealWithRecursion(int f);
int dealWithNoRecursion(int f);
// to save the result.
int arr[N];
 
int main(void) {
    int floor;
    scanf("%d", &floor);
    floor %= 21;
    if (MODE == RECUR) {
        printf("%d\n", dealWithRecursion(floor));
    } else {
        memset(arr, 0, sizeof(arr));
        printf("%d\n", dealWithNoRecursion(floor));
    }
    return 0;
}
 
int dealWithRecursion(int f) {
    if (f == 1 || f == 0) return 1;
    return (dealWithRecursion(f - 1) + dealWithRecursion(f - 2));
}
 
int dealWithNoRecursion(int f) {
    if (arr[f] != 0) return arr[f];
    int result;
    if (f == 0 || f == 1) result = 1;
    else result = dealWithNoRecursion(f - 1) + dealWithNoRecursion(f - 2);
    arr[f] = result;
    return result;
}