数手指

描述：从右手大拇指数数，从1开始，至小拇指后颠倒顺序至大拇指，至大拇指后颠倒顺序至小拇指,请问第n次后第几根手指

   function findN(num){
        let stack = [1,2,3,4,5,4,3,2]; //[] 1 2 3 4 5 4 3 2 1 2 3 4 5 4 3 2 1 2 3 4 5 4 3 2 1 2
        // 解法1 找规律
        let index = num % 8;
        let returnVal = stack[index - 1];
        return returnVal;
         
    }
    console.log(findN(1314))