//: Playground - noun: a place where people can play

//import UIKit
/*
 逆时针打印N*N矩阵
 */


func anticlockwiseNN(n:Int){
    var m=1;
    var a = [[Int]]();
    for _ in 0..<n {
        //初始化矩阵元素为0
        var b = [Int]()
        for _ in 0..<n {
            b.append(0)
            
        }
        
        a.append(b)
        
    }
    for i in 0 ..< n/2 {  //只旋转n/2次
        for j in i ..< (n-i) { //向下
            if(a[j][i] == 0){
                
                a[j][i] = m ;
                m = m + 1 ;
            }
        }
        
        for j in (i + 1 ) ..< (n-i) { //向右
            if a[n-i-1][j] == 0 {
                
                a[n-i-1][j] = m
                m = m + 1
            }
        }
        
        for j in  (i ..< (n-i-1)).reversed()  { //向上
            if a[j][n-i-1] == 0 {
                a[j][n-i-1] = m
                m = m + 1
            }
        }
        
        for j in ((i + 1 ) ..< (n-i-1)).reversed(){ //向左
            if a[i][j] == 0 {
                
                a[i][j] = m ;
                m = m + 1
            }
        }
        
        
        
        
    }
    
    
    if(n%2==1){//注意！当n为奇数时，有个正中心点
        a[n/2][n/2] = m;
    }
    
    
    for i in 0..<n {
        //初始化矩阵元素为0
        var s = "";
        for j in 0..<n {
            if a[i][j] < 10 {
                s = s + "0"
            }
            s = s + String(a[i][j]) + " "
        }
        print(s)
    }
}


anticlockwiseNN(n: 5)