题解 | #螺旋矩阵#

import java.util.ArrayList;
public class Solution {
    public ArrayList<Integer> spiralOrder(int[][] matrix) {
        ArrayList<Integer> list = new ArrayList<Integer>();
        //求m、n值
        int m = matrix.length;
        if (m == 0)
            return list;
        int n = matrix[0].length;
        
        
        //设置数组的上、下、左、右值，随循环调整
        int top = 0;
        int bottom = m-1;
        int left = 0;
        int right = n-1;
        //循环，采用螺旋方法读取，每次取完一行或一列数后对四个值操作并检查
        while (top<=bottom && left<=right) {
            for (int j = left; j<=right; j++) {
                list.add(matrix[top][j]);
            }
            ++top;
            if (top>bottom)
                break;
            for (int i = top; i<=bottom; i++) {
                list.add(matrix[i][right]);
            }
            --right;
            if (left>right)
                break;
            for (int j = right; j>=left; j--) {
                list.add(matrix[bottom][j]);
            }
            --bottom;
            if (top>bottom)
                break;
            for (int i = bottom; i>=top; i--) {
                list.add(matrix[i][left]);
            }
            ++left;
            if (left>right)
                break;
        }
        
        return list;
    }
}