M螺旋矩阵 ||（leetcode59）

/**
 * @param {number} n
 * @return {number[][]}
 */
var generateMatrix = function(n) {
    const maxNum = n * n;
    let curNum = 1;
    const matrix = new Array(n).fill(0).map(() => new Array(n).fill(0));
    let row = 0,column = 0;
    const directions = [[0, 1], [1, 0], [0, -1], [-1, 0]]; //右下左上
    let directionIndex = 0;
    while (curNum <= maxNum) {
        matrix[row][column] = curNum;
        curNum++;
        const nextRow = row + directions[directionIndex][0], nextColumn = column + directions[directionIndex][1];
        if (nextRow < 0 || nextRow >= n || nextColumn < 0 || nextColumn >= n || matrix[nextRow][nextColumn] !== 0) {
            directionIndex = (directionIndex + 1) % 4; //顺时针旋转至下一个方向
        }
        row = row + directions[directionIndex][0];
        column = column + directions[directionIndex][1];
    }
    return matrix;
};

M螺旋矩阵（leetcode54）

/**
 * @param {number[][]} matrix
 * @return {number[]}
 */
var spiralOrder = function(matrix) {
    let left = 0; //四个边界
    let right = matrix[0].length - 1;
    let top = 0;
    let bottom = matrix.length - 1;
    let res = []; //存储结果
    while(true) {
        for(let i = left; i <= right; i++) {
            res.push(matrix[top][i]);
        }
        top++;
        if (top > bottom) break; // 四个边，每个边结束都判断是否终止
        for (let i = top; i <= bottom; i++) {
            res.push(matrix[i][right]);
        }
        right--;
        if (right < left) break;
        for (let i = right; i >= left; i--) {
            res.push(matrix[bottom][i]);
        }
        bottom--;
        if(bottom < top) break;
        for(let i = bottom; i >= top;i--) {
            res.push(matrix[i][left]);
        }
        left++;
        if(left > right) break;
    }
    return res;
};

E螺旋遍历二维数组（leetcode146）

/**
 * @param {number[][]} array
 * @return {number[]}
 */
var spiralArray = function(array) {
    if (!array.length || !array[0].length) {
        return [];
    }
    const rows = array.length, columns = array[0].length;
    const visited = new Array(rows).fill(0).map(() => new Array(columns).fill(false));
    const total = rows * columns;
    const order = new Array(total).fill(0);

    let directionIndex = 0, row = 0, column = 0;
    const directions = [[0, 1], [1, 0], [0, -1], [-1, 0]];
    for (let i = 0; i < total; i++) {
        order[i] = array[row][column];
        visited[row][column] = true;
        const nextRow = row + directions[directionIndex][0], nextColumn = column + directions[directionIndex][1];
        if (!(0 <= nextRow && nextRow < rows && 0 <= nextColumn && nextColumn < columns && !(visited[nextRow][nextColumn]))) {
            directionIndex = (directionIndex + 1) % 4;
        }
        row += directions[directionIndex][0];
        column += directions[directionIndex][1];
    }
    return order;
};