使用遞歸反向打印

Question

我剛開始使用遞歸，似乎無法理解以下將如何發生。 我想打印從i = 2到i = 6的值。 目前，它正在以相反的順序打印。 請你幫助我好嗎？

int l[][7] ={{0,0,0,0,0,0,0},{0,0,1,2,1,1,2},{0,0,1,2,1,2,2}};
int lstar = 1;
int recprint(int n, int i){
    if (i>n)
    {
        return lstar;
    }
    else{
        int m =  recprint(n, i+1);
        printf("i is %d and l[%d][%d] is %d \n", i, m, i , l[m][i]);
        return l[m][i];
    }
}
recprint(6, n);

output 需要的是

i is 6 and l[1][6] is 2     
i is 5 and l[2][5] is 2     
i is 4 and l[2][4] is 1     
i is 3 and l[1][3] is 2      
i is 2 and l[2][2] is 1 

相反

Answer 1

void recprint(int i, int j, int val = 1) {
  if (i < j) {
    return;
  }
  recprint(i - 1, j, l[val][i]);
  printf("i is %d and l[%d][%d] is %d\n", i, val, i, l[val][i]);
}

recprint(6, 2);

Output：

i is 2 and l[2][2] is 1 
i is 3 and l[1][3] is 2 
i is 4 and l[2][4] is 1 
i is 5 and l[2][5] is 2 
i is 6 and l[1][6] is 2