一维数组的翻转

// 一维矩阵翻转
// 实例： arr = [1,2,3,4,5] => [5,4,3,2,1]
let n  = readline()
let arr = readline().split(' ').map(Number)
// console.log(n,arr)
let temp = 0
for(let i = 0; i < n/2;i++){temp = arr[i]arr[i] = arr[n-i-1]arr[n-i-1] = temp
}
console.log(arr)

n*n矩阵的翻转

1. 水平翻转

// 二维矩阵水平翻转
// 实例
// 1 2 3            7 8 9
// 4 5 6      =》   4 5 6
// 7 8 9            1 2 3
let n = readline()
var arr = []
for(let i = 0; i < n;i++){arr[i] = readline().split(' ').map(Number)// for(let j = 0;j < n;j++){//     arr[i][j] = arr[i][j]// }
}
// console.log('a',arr)
for(let i = 0; i <= n/2; i++){for(let j = 0; j < n;j++){let temp = 0;temp = arr[i][j]arr[i][j] = arr[n-i-1][j]arr[n-i-1][j] = temp}
}
console.log(arr)

2. 垂直翻转

// 二维矩阵垂直翻转
// 实例
// 1 2 3            3 2 1
// 4 5 6      =》   6 5 4
// 7 8 9            9 8 7
let n = readline()
var arr = []
for(let i = 0; i < n;i++){arr[i] = readline().split(' ').map(Number)// for(let j = 0;j < n;j++){//     arr[i][j] = arr[i][j]// }
}
console.log('a',arr[0][0])
let temp
for(let i = 0; i < n; i++){for(let j = 0; j <= n/2;j++){console.log(temp)temp = arr[i][j]arr[i][j] = arr[i][n-j-1]arr[i][n-j-1] = temp}
}
console.log(arr)

3. 水平垂直方向各翻转一次

// 二维矩阵水平垂直各翻转一次
// 实例 
// 1 2 3            9 8 7
// 4 5 6      =》   6 5 4
// 7 8 9            3 2 1
let n = readline()
var arr = new Array()//定义一维数组
for(let i = 0 ; i < n ; i++){arr[i] = readline().split(' ').map(Number)
}
// var result = [[],[],[]]
var result = []
//reverse(arr)// console.log(arr)
//function reverse(arr){for(let i = 0; i < n;i++){ for(let j = 0; j <= n/2;j++){let temp = 0;temp = arr[i][j];arr[i][j] = arr[i][n-j-1];arr[i][n-j-1] = temp}result[n-i-1] = arr[i]}console.log(result)// document.write('<br>');
//}