83 lines
1.6 KiB
Markdown
83 lines
1.6 KiB
Markdown
# 螺旋矩阵
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## 题目
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给你一个 m 行 n 列的矩阵 matrix ，请按照 顺时针螺旋顺序 ，返回矩阵中的所有元素。
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示例 1：
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输入：matrix = [[1,2,3],[4,5,6],[7,8,9]]
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输出：[1,2,3,6,9,8,7,4,5]
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示例 2：
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输入：matrix = [[1,2,3,4],[5,6,7,8],[9,10,11,12]]
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输出：[1,2,3,4,8,12,11,10,9,5,6,7]
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提示：
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m == matrix.length
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n == matrix[i].length
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1 <= m, n <= 10
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-100 <= matrix[i][j] <= 100
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## 思路
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- 模拟
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- 方向
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- →↓←↑
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- 边界
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- `up`
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- `down`
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- `left`
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- `right`
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## 代码
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```java
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class Solution {
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public List<Integer> spiralOrder(int[][] matrix) {
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// Init: up, down, left, right
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int up = 0;
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int down = matrix.length - 1;
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int left = 0;
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int right = matrix[0].length - 1;
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// Init: ans
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List<Integer> ans = new ArrayList<>();
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int tar = matrix.length * matrix[0].length;
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// Traverse
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while (left <= right && up <= down) {
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for (int i = left; i <= right; i++) {
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ans.add(matrix[up][i]);
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}
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up ++;
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for (int i = up; i <= down; i++) {
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ans.add(matrix[i][right]);
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}
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right --;
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if (up <= down) {
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for (int i = right; i >= left; i--) {
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ans.add(matrix[down][i]);
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}
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}
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down --;
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if (left <= right) {
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for (int i = down; i >= up; i--) {
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ans.add(matrix[i][left]);
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}
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}
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left ++;
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}
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return ans;
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}
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}
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``` |