PrintTheMatrixClockwise.java

package swordPointOffer;

/**
 * @Author: Wenhang Chen
 * @Description:输入一个矩阵，按照从外向里以顺时针的顺序依次打印出每一个数字。  
 * <p>
 * 示例 1：
 * <p>
 * 输入：matrix = [[1,2,3],[4,5,6],[7,8,9]]
 * 输出：[1,2,3,6,9,8,7,4,5]
 * 示例 2：
 * <p>
 * 输入：matrix = [[1,2,3,4],[5,6,7,8],[9,10,11,12]]
 * 输出：[1,2,3,4,8,12,11,10,9,5,6,7]
 *  
 * <p>
 * 限制：
 * <p>
 * 0 <= matrix.length <= 100
 * 0 <= matrix[i].length <= 100
 * @Date: Created in 8:58 4/2/2020
 * @Modified by:
 */
public class PrintTheMatrixClockwise {
    public int[] spiralOrder(int[][] matrix) {
        if (matrix.length == 0) return new int[0];
        int l = 0, r = matrix[0].length - 1, t = 0, b = matrix.length - 1, x = 0;
        int[] res = new int[(r + 1) * (b + 1)];
        while (true) {
            for (int i = l; i <= r; i++) res[x++] = matrix[t][i]; // left to right.
            if (++t > b) break;
            for (int i = t; i <= b; i++) res[x++] = matrix[i][r]; // top to bottom.
            if (l > --r) break;
            for (int i = r; i >= l; i--) res[x++] = matrix[b][i]; // right to left.
            if (t > --b) break;
            for (int i = b; i >= t; i--) res[x++] = matrix[i][l]; // bottom to top.
            if (++l > r) break;
        }
        return res;
    }
}