题目链接:https://leetcode-cn.com/problems/shun-shi-zhen-da-yin-ju-zhen-lcof/
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。
输入:matrix = [[1,2,3],[4,5,6],[7,8,9]]
输出:[1,2,3,6,9,8,7,4,5]
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]
解题过程:
关键思想:每遍历一行或者一列,都更新矩阵的边界
。
每次遍历矩阵,总有一个坐标是边界值,另一个坐标值位于两个边界值之间,所以处理好边界值即可。
遍历分:从左到右,从上到下,从右到左,从下到上
这四种。
class Solution {
public int[] spiralOrder(int[][] matrix) {
int row = matrix.length;
if (row == 0)
return new int[0];
int col = matrix[0].length;
int[] res = new int[row * col];
int index = 0;
int left = 0, right = col - 1, bottom = row - 1, top = 0;
while (true) {
for (int i = left; i <= right; i++) {
res[index++] = matrix[top][i];
}
if (++top > bottom)
break;
for (int i = top; i <= bottom; i++) {
res[index++] = matrix[i][right];
}
if (--right < left)
break;
for (int i = right; i >= left; i--) {
res[index++] = matrix[bottom][i];
}
if (--bottom < top)
break;
for (int i = bottom; i >= top; i--) {
res[index++] = matrix[i][left];
}
if (++left > right)
break;
}
return res;
}
}