题目
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。例如，如果输入如下矩阵：
1 2 3 4
5 6 7 8
9 10 11 12
13 14 15 16
则依次打印出数字1, 2, 3, 4, 8, 12, 16, 15, 14, 13, 9, 5, 6, 7, 11 , 10 限制：
- 0 <= matrix.length <= 100
- 0 <= matrix[i].length <= 100
题解
按层遍历
/**
* @param {number[][]} matrix
* @return {number[]}
*/
var spiralOrder = function(matrix) {
if (!matrix.length || !matrix[0].length) {
return [];
}
const rows = matrix.length, columns = matrix[0].length;
const order = [];
let left = 0, right = columns - 1, top = 0, bottom = rows - 1;
while (left <= right && top <= bottom) {
for (let column = left; column <= right; column++) {
order.push(matrix[top][column]);
}
for (let row = top + 1; row <= bottom; row++) {
order.push(matrix[row][right]);
}
if (left < right && top < bottom) {
for (let column = right - 1; column > left; column--) {
order.push(matrix[bottom][column]);
}
for (let row = bottom; row > top; row--) {
order.push(matrix[row][left]);
}
}
[left, right, top, bottom] = [left + 1, right - 1, top + 1, bottom - 1];
}
return order;
};
复杂度分析
- 时间复杂度：O(mn)
- 空间复杂度：O(1)
引用
- 剑指offer书籍
- 力扣题解
