Leetcode skimming - super power 372 medium

Super power thinking and source code
     The title of super power is shown in the figure below , This problem belongs to mathematics and divide and conquer , It mainly examines the use of recursive methods and the understanding of mathematical ideas of the topic . The title of this article, the author thought 2 Methods , They are reverse order traversal method and positive order traversal method , The reverse traversal method uses Java Compiling , The positive order traversal method uses Python Compiling , Of course, this may not be the optimal solution , I also hope you guys can give a faster algorithm .

     I think this problem can be solved by the idea of reverse traversal , First, implement a function that iterates in reverse order to calculate the power , The function is initialized internally , Then judge whether the current incoming number is 0, If not for 0 Then start traversing , Judge whether the number is odd , If it is an odd number, the numbers are iterated in reverse order , Until the traversal is over and the result is returned . And in the main function , Initialize a number first , Then start traversing the loop , After calling the function to calculate the power and the current historical results, calculate and perform the remainder operation , Until the loop traversal ends , Return the final result to . Then according to this idea, our Java The code is as follows ：

# Fire breathing dragon and water arrow turtle 
class Solution {
    static final int IND = 1337;
    public int superPow(int a, int[] b) {
        int res = 1;
        for (int ir = b.length - 1; ir >= 0;ir--) {
            res = (int) ((long) res * pow(a, b[ir]) % IND);
            a = pow(a, 10);
        }
        return res;
    }

    public int pow(int x, int n) {
        int vex = 1;
        while (n != 0) {
            if (n % 2 != 0) {
                vex = (int) ((long) vex * x % IND);
            }
            x = (int) ((long) x * x % IND);
            n = n/2;
        }
        return vex;
    }
}

     obviously , The effect of our reverse traversal method is general , At the same time, it can also be solved by positive order traversal . Initialize the parameters first , Then start traversing the loop , Call the result directly to the power function of the system for iterative positive order calculation , Until the end of the final cycle and return the result . So according to this idea, we can solve , Here is Python Code ：

# Fire breathing dragon and water arrow turtle 
class Solution:
    def superPow(self, a: int, b: List[int]) -> int:
        NUM = 1337
        res = 1
        for jr in b:
            res = pow(res, 10, NUM) * pow(a, jr, NUM) % NUM
        return res

     As a result Java The efficiency of version reverse traversal method is general , and Python The speed of the positive sequence traversal method of version is also relatively general , But there should be more ways to further speed up , I hope friends can give me more advice , Thank you very much .