面试题29. 顺时针打印矩阵

面试题29. 顺时针打印矩阵

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顺时针打印矩阵

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。

示例 1:

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:

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]

思路

限制边界,同时注意边界的限制条件

解答

class Solution {
    public int[] spiralOrder(int[][] matrix) {
        if (matrix.length == 0) return new int[0];

        int left = 0, right = matrix[0].length - 1, top = 0, bottom = matrix.length - 1;
        int x = 0;
        int [] result = new int[(right + 1) * (bottom + 1)];
        while (true) {
            for (int i = left; i <= right; i++) result[x++] = matrix[top][i];
            if (++top > bottom) break;

            for (int i = top; i <= bottom; i++) result[x++] = matrix[i][right];
            if (left > --right) break;

            for (int i = right; i >= left; i--) result[x++] = matrix[bottom][i];
            if (top > --bottom) break;

            for (int i = bottom; i >= top; i--) result[x++] = matrix[i][left];
            if (++left > right) break;
        }
        return result;
    }
}