题解 | #螺旋矩阵#

import java.util.*;

public class Solution {
    public ArrayList<Integer> spiralOrder(int[][] matrix) {
        ArrayList<Integer> arr = new ArrayList<Integer>();
        if(matrix.length == 0) return arr;
        int top = 0;
        int left = 0;
        int right = matrix[0].length - 1;
        int bottom = matrix.length - 1;
        while(left <= right && top <= bottom){
            for(int col = left; col <= right; col++){
                arr.add(matrix[top][col]);
            }
            if(++top > bottom) break;
            for(int row = top; row <= bottom; row++){
                arr.add(matrix[row][right]);
            }
            if(--right < left) break;
            for(int col = right; col >= left; col--){
                arr.add(matrix[bottom][col]);
            }
            if(--bottom < top) break;

            for(int row = bottom; row >= top; row--){
                arr.add(matrix[row][left]);
            }
            if(++left > right) break;
        }
        return arr;
    }
}