题解 | 牛牛学数列6

#include <stdio.h>
int shulie(int n){
    if(n==1) return 0;
    if(n==2 || n==3) return 1;
    else return (shulie(n-3)+2*shulie(n-2)+shulie(n-1));/递归

}
int main() {
    int n;
    scanf("%d",&n);
    int m = shulie(n);
    printf("%d",m);
    return 0;
}