Snail

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Snail

题目地址：

Snail Sort

Given an n x n array, return the array elements arranged from outermost elements to the middle element, traveling clockwise.

array = [[1,2,3],[4,5,6],[7,8,9]]
snail(array) #=> [1,2,3,6,9,8,7,4,5]

For better understanding, please follow the numbers of the next array consecutively:

array = [[1,2,3],[8,9,4],[7,6,5]]
snail(array) #=> [1,2,3,4,5,6,7,8,9]

思路：外圈遍历到内圈，顺时针遍历

javascript版本

1.自己

snail = function(array) {// enjoylet result = [];while(array.length){// 右方向result = result.concat(array.shift());// 下方向for(let i = 0 ; i < array.length ; i++){result.push(array[i].pop());}// 左方向result = result.concat((array.pop()||[]).reverse());// 上方向for(let j = array.length-1 ; j >= 0 ; j--){result.push(array[j].shift());}}return result;
}

2.他人

function snail(array) {var vector = [];while (array.length) {vector.push(...array.shift());array.map(row => vector.push(row.pop()));array.reverse().map(row => row.reverse());}return vector;
}

3.他人（目前还没看懂）

snail = function(array) {var size = array.length;if (size == 0)return [];if (size == 1)return array[0];var top    = array[0].slice(0, -1);var right  = array.slice(0, -1).map(a => a[size - 1]);var bottom = array[size -1].slice(1).reverse();var left   = array.slice(1).map(a => a[0]).reverse();var inner  = array.slice(1, -1).map(a => a.slice(1, -1));return [].concat(top, right, bottom, left, snail(inner));
}

4.他人（目前还没看懂）

snail = function(array) {var res = [];while(array.length) {res = res.concat(array.shift())array = expand(array);}return res;
}function expand(matrix){return matrix.reduce(function(res, arr, i){arr.forEach(function(n, j){if (!res[j]) res[j] = [];res[j][i] = n;})return res;}, []).reverse();
}