模板

打印图示：

class Solution {
    public List<Integer> spiralOrder(int[][] matrix) {
        if (matrix == null || (matrix.length == 0 && matrix[0].length == 0)) return res;
        int top = 0, bottom = matrix.length - 1, left = 0, right = matrix[0].length - 1;
        while (left <= right && top <= bottom) {
            for (int column = left; column <= right; column++) {
                res.add(matrix[top][column]);
            }
            for (int row = top + 1; row <= bottom; row++) {
                res.add(matrix[row][right]);
            }
            // if判断是根据是否时正方形，如果不是需要判断，如果是就不需要判断
            if (left < right && top < bottom) {
                for (int column = right - 1; column >= left + 1; column--) {
                    res.add(matrix[bottom][column]);
                }
                for (int row = bottom; row >= top + 1; row--) {
                    res.add(matrix[row][left]);
                }
            }
            top++;
            bottom--;
            left++;
            right--;
        }
        return res;
    }
}

59.矩阵模拟II

🔗

public int[][] generateMatrix(int n) {
    int[][] array = new int[n][n];
    int top = 0, bottom = n - 1, left = 0, right = n - 1;
    int count = 1;
    while (left <= right && top <= bottom) {
        for (int column = left; column <= right; column++) {
            array[top][column] = count++;
        }
        for (int row = top + 1; row <= bottom; row++) {
            array[row][right] = count++;
        }
        for (int column = right - 1; column >= left + 1; column--) {
            array[bottom][column] = count++;
        }
        for (int row = bottom; row >= top + 1; row--) {
            array[row][left] = count++;
        }
        top++;
        bottom--;
        left++;
        right--;
    }
    return array;
}

54.螺旋矩阵

public List<Integer> spiralOrder(int[][] matrix) {
    List<Integer> res = new ArrayList<>();
    if (matrix == null || (matrix.length == 0 && matrix[0].length == 0)) return res;
    int top = 0, bottom = matrix.length - 1, left = 0, right = matrix[0].length - 1;
    while (left <= right && top <= bottom) {
        for (int column = left; column <= right; column++) {
            res.add(matrix[top][column]);
        }
        for (int row = top + 1; row <= bottom; row++) {
            res.add(matrix[row][right]);
        }
        if (left < right && top < bottom) {
            for (int column = right - 1; column >= left + 1; column--) {
                res.add(matrix[bottom][column]);
            }
            for (int row = bottom; row >= top + 1; row--) {
                res.add(matrix[row][left]);
            }
        }
        top++;
        bottom--;
        left++;
        right--;
    }
    return res;
}

剑指 Offer 29. 顺时针打印矩阵

🔗

public int[] spiralOrder(int[][] matrix) {
    if (matrix == null || matrix.length == 0 || matrix[0].length == 0) {
        return new int[]{};
    }
    List<Integer> list = new ArrayList<>();
    int rows = matrix.length, columns = matrix[0].length; // 行列的数量
    int top = 0, button = rows - 1, right = columns - 1, left = 0;
    while (left <= right && top <= button) {
        // 遍历上边
        for (int column = left; column <= right; column++) {
            list.add(matrix[top][column]);
        }
        // 遍历右边
        for (int row = top + 1; row <= button; row++) {
            list.add(matrix[row][right]);
        }
        if (left < right && top < button) {
            // 遍历下边
            for (int column = right - 1; column > left; column--) {
                list.add(matrix[button][column]);
            }
            // 遍历左边
            for (int row = button; row > top; row--) {
                list.add(matrix[row][left]);
            }
        }
        left++;
        right--;
        top++;
        button--;
    }
    int[] ints = new int[list.size()];
    for (int i = 0; i < list.size(); i++) {
        ints[i] = list.get(i);
    }
    return ints;
}