2*1, 2*2 타일링 더블릿

#include <stdio.h>
#include <algorithm>
#include <cstring>
 
using namespace std;
 
int numA[1000] = { 0 };
int numB[1000] = { 0 };
int result[1000] = { 0 };
 
void NumSort(int* arr, int* idx) {
    for (int i = 0; i <= *idx; i++) {
        if (arr[i] >= 10) {
            if (i == *idx) {                
                *idx += 1;
            }
            arr[i + 1] += (arr[i] / 10);
            arr[i] %= 10;
        }
    }
}
 
int main() {
    int n,idxA=0,idxB=0,len;
    scanf("%d", &n);
 
    numA[idxA] = 1;
    numB[idxB] = 3;
 
    if (n < 3) {
        if (n == 1) {
            printf("1");
            return 0;
        }
        if (n == 2) {
            printf("2");
            return 0;
        }
    }
 
    for (int i = 0; i < n-2; i++) {
        for (int j = 0; j <= idxA; j++) {
            numA[j] = numA[j] * 2;
        }
        NumSort(numA, &idxA);        
 
        len = max(idxA, idxB);
        for (int j = 0; j <= len; j++) {
            result[j] = numA[j] + numB[j];
        }
        NumSort(result, &len);
 
        memcpy(numA, numB, 1000 * sizeof(int));
        memcpy(numB, result, 1000 * sizeof(int));
        idxA = idxB;
        idxB = len;
    }    
    for (int i = len; i >= 0; i--) {
        printf("%d", result[i]);
    }
}