单个循环输出数圈（简单易懂）

// IntegerRing.cpp : 定义控制台应用程序的入口点。
//

/*
题目描述
以1为中心，用2,3,4, ..., n, ..., n*n的数字围绕着中心输出数圈， 如若n=4，则
7 8 9 10
6 1 2 11
5 4 3 12
16 15 14 13
输入
一个整数n(1<=n<=10)
输出
数圈矩阵
样例输入
5
样例输出
21 22 23 24 25
20 7  8  9  10
19 6  1  2  11
18 5  4  3  12
17 16 15 14 13
*/

#include "stdafx.h"
#include <math.h>


int main()
{
    int n = 0, c = 0, r = 0;
    printf_s("请输入一个整数n(1<=n<=10)：\n");
    scanf_s("%d", &n);
    const int arrLength = n*n;
    int* pArr = new int[arrLength];
    c = n / 2;    //行
    r = n / 2;    //列
    if (n % 2 == 0)
    {
        --c;
        --r;
    }

    // 1在数组中的位置
    int index = r * n + c, preIndex = 0;
    pArr[index] = 1;
    preIndex = index;
    //方向，列走的方向有rgiht、left，行走的方向down、up。
    int cRight = 1, rDown = 1, cLeft = -1, rUp = -1;
    bool fIsReverse = false, fIsH = true;
    if (n > 0 && n < 11)
    {
        int times = 0 , countTimes = 1;
        for (int i = 0; i < arrLength - 1; ++i)
        {
            ++times;
            if (fIsH)
            {
                if (!fIsReverse)
                {
                    c+=cRight;
                    if (times == countTimes)
                    {
                        //改变方向
                        fIsH = !fIsH;
                        times = 0;
                    }
                }
                else
                {
                    c+=cLeft;
                    if(times == countTimes)
                    {
                        fIsH = !fIsH;
                        times = 0;
                    }
                }
            }
            else
            {
                if (!fIsReverse)
                {
                    r+=rDown;
                    if (times == countTimes)
                    {
                        //改变方向
                        fIsH = !fIsH;
                        fIsReverse = !fIsReverse;
                        times = 0;
                        ++countTimes;
                    }
                }
                else
                {
                    r+=rUp;
                    if (times == countTimes)
                    {
                        //改变方向
                        fIsH = !fIsH;
                        fIsReverse = !fIsReverse;
                        times = 0;
                        ++countTimes;
                    }
                }
            }

            index = r * n + c;
            pArr[index] = pArr[preIndex] + 1;
            preIndex = index;
        }
    }
    
    for (int i = 0; i < arrLength; ++i)
    {
        printf_s("%d ", pArr[i]);
        if (i % n == n - 1)
        {
            printf_s("\n");
        }
    }
    
    main();
    return 0;
}