c - 甚至以向后方式排列数组的字符串

Question

我正在尝试打印一个数组，以便向后打印偶数字符串，但以通常的方式打印非偶数字符串。我做错了什么？例如:

1 0 3
9 7 3
5 7 8

我需要它:

1 0 3
3 7 9
5 7 8

但是我也遇到了以螺旋方式填充数组的问题；我应该如何取数组的中心？请您提供一个想法——我该怎么做？并且数组必须是正方形的。例如:

1 2 3
4 5 6
7 8 9

但我需要它:

3 2 9
4 1 8
5 6 7

到目前为止我的代码:

#include <stdio.h>
#include <stdlib.h>


int main()
{
    int a[10][10],n,m,i,j;

    printf("Enter m: ");
    scanf("%d",&m);
    printf("Enter n: ");
    scanf("%d",&n);
    for(i=0;i<m;i++){
            for(j=0;j<m;j++){
                    printf("a[%d][%d]: ",i+1,j+1);
       scanf("%d",&a[i][j]);
            }
    }

// in usual order
    for(i=0;i<m;i++){
            for(j=0;j<n;j++){
            printf("%d ",a[i][j]);
                }
                printf("\n");
        }


        for(i=0;i<m;i++){
            for(j=0;j<n;j++){
            if(i%2 != 0){
            printf("%d ",a[i][j]);
            }
              else {
                    printf("%d ",a[n-i+1][j]);
                }
            }
            printf("\n");
        }

    return 0;
}

Answer 1

螺旋填充数组的示例

#include <stdio.h>
#include <string.h>

typedef enum {
    N, W, S, E
} Dir;

typedef struct walker {
    int row, col;
    Dir dir;
    int steps;
} Walker;

Walker go_forward(Walker walker){
    switch(walker.dir){
    case N:
        walker.row -= 1;
        break;
    case W:
        walker.col -= 1;
        break;
    case S:
        walker.row += 1;
        break;
    case E:
        walker.col += 1;
        break;
    }
    return walker;
}

Walker proceed_left(Walker walker){
    walker.dir = (walker.dir + 1) % 4;//turn left
    walker = go_forward(walker);
    return walker;
}

int main(void){
    int n;
    for(;;){
        printf("Enter n(0 < n < 10): ");fflush(stdout);
        int ret_s = scanf("%d", &n);
        if(ret_s == 1){
            if(0 < n && n < 10)
                break;
        } else if(ret_s == 0)
            while(getchar() != '\n');//clear input
        else //if(ret_s == EOF)
            return 0;
    }
    int a[n][n];
    memset(a, 0, sizeof(a));//zero clear
    Walker walker = { .row = n / 2, .col = n / 2, .dir = E, .steps = 0 };
    for(;;){
        walker.steps += 1;
        a[walker.row][walker.col] = walker.steps;
        if(walker.steps == n * n)//goal
            break;
        Walker left = proceed_left(walker);
        if(a[left.row][left.col] == 0)//left side is vacant
            walker = left;
        else
            walker = go_forward(walker);
    }
    for(int r = 0; r < n; ++r){
        for(int c = 0; c < n; ++c){
            if(c)
                putchar(' ');
            printf("%2d", a[r][c]);
        }
        puts("");
    }
}