题解 | 牛牛学数列6

#include <stdio.h>
int  shulie (int num){
    if (num==1){
        return 0;
    }
    if (num==2||num==3){
        return 1;
        
    }
    else {
    return shulie(num-3)+2*shulie(num-2)+shulie(num-1);
    }
}
int main () {
    int n;
    scanf("%d",&n);
    printf("%d",shulie(n));
    return 0;
}