【Leecode】Leecode刷题之路第54天之旋转矩阵

题目出处

54-螺旋矩阵-题目出处

题目描述

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个人解法

思路：

todo

代码示例：（Java）

todo

复杂度分析

todo

官方解法

54-旋转矩阵-官方解法

方法1：模拟

思路：

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代码示例：（Java）

public class Solution1 {public List<Integer> spiralOrder(int[][] matrix) {List<Integer> order = new ArrayList<Integer>();if (matrix == null || matrix.length == 0 || matrix[0].length == 0) {return order;}int rows = matrix.length, columns = matrix[0].length;boolean[][] visited = new boolean[rows][columns];int total = rows * columns;int row = 0, column = 0;int[][] directions = {{0, 1}, {1, 0}, {0, -1}, {-1, 0}};int directionIndex = 0;for (int i = 0; i < total; i++) {order.add(matrix[row][column]);visited[row][column] = true;int nextRow = row + directions[directionIndex][0], nextColumn = column + directions[directionIndex][1];if (nextRow < 0 || nextRow >= rows || nextColumn < 0 || nextColumn >= columns || visited[nextRow][nextColumn]) {directionIndex = (directionIndex + 1) % 4;}row += directions[directionIndex][0];column += directions[directionIndex][1];}return order;}}

复杂度分析

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方法2:按层模拟

思路：

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代码示例：（Java）

public class Solution2 {public List<Integer> spiralOrder(int[][] matrix) {List<Integer> order = new ArrayList<Integer>();if (matrix == null || matrix.length == 0 || matrix[0].length == 0) {return order;}int rows = matrix.length, columns = matrix[0].length;int left = 0, right = columns - 1, top = 0, bottom = rows - 1;while (left <= right && top <= bottom) {for (int column = left; column <= right; column++) {order.add(matrix[top][column]);}for (int row = top + 1; row <= bottom; row++) {order.add(matrix[row][right]);}if (left < right && top < bottom) {for (int column = right - 1; column > left; column--) {order.add(matrix[bottom][column]);}for (int row = bottom; row > top; row--) {order.add(matrix[row][left]);}}left++;right--;top++;bottom--;}return order;}}