[LeetCode 54]Spiral Matrix

题目链接：spiral-matrix

import java.util.ArrayList;import java.util.List;/** * Given a matrix of m x n elements (m rows, n columns), return all elements of the matrix in spiral order.For example,Given the following matrix:[ [ 1, 2, 3 ], [ 4, 5, 6 ], [ 7, 8, 9 ]]You should return [1,2,3,6,9,8,7,4,5]. * */public class SpiralMatrix {//21 / 21 test cases passed.//Status: Accepted//Runtime: 170 ms//Submitted: 0 minutes agostatic List<Integer> spiralOrder(int[][] matrix) {List<Integer> orders = new ArrayList<Integer>();if(matrix.length == 0) return orders;int m = matrix.length;int n = matrix[0].length;//up// leftright//downint left = 0;int right = n – 1;int up = 0;int down = m – 1;while(left <= right && up <= down) {for(int i = left; i <= right; i ++) {orders.add(matrix[up][i]);}up ++;for(int i = up; i <= down; i ++) {orders.add(matrix[i][right]);}right –;for(int i = right; i >= left && up <= down; i –) {orders.add(matrix[down][i]);}down –;for(int i = down; i >= up && left <= right; i –) {orders.add(matrix[i][left]);}left ++;}return orders;}public static void main(String[] args) {//int[][] matrix = {{1,2, 3}, {4, 5, 6}, {7, 8, 9}};int[][] matrix = {{2, 3}};for (int n : spiralOrder(matrix)) {System.out.print(n + ", ");}}}

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