【剑指Offer】顺时针打印矩阵

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。

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]

限制:

0 <= matrix.length <= 100
0 <= matrix[i].length <= 100

题解

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class Solution {
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;
}
}