【矩阵】54.螺旋矩阵（顺时针打印矩形元素）

题目

class Solution {public List<Integer> spiralOrder(int[][] matrix) {int m = matrix.length, n = matrix[0].length;int leftUpM = 0, leftUpN = 0, rightDownM = m - 1, rightDownN = n - 1;List<Integer> res = new ArrayList<>();while (leftUpM <= rightDownM && leftUpN <= rightDownN) {for (int i = leftUpN; i <= rightDownN; ++i) { // 向右res.add(matrix[leftUpM][i]);}for (int i = leftUpM + 1; i < rightDownM; ++i) { // 向下res.add(matrix[i][rightDownN]);}for (int i = rightDownN; i >= leftUpN && leftUpM < rightDownM; --i) { // 向左res.add(matrix[rightDownM][i]);}for (int i = rightDownM - 1; i > leftUpM && leftUpN < rightDownN; --i) { // 向上res.add(matrix[i][leftUpN]);}++leftUpM;++leftUpN;--rightDownM;--rightDownN;}return res;}
}