mirror of
https://github.com/chefyuan/algorithm-base.git
synced 2024-12-29 05:46:17 +00:00
363 lines
10 KiB
Java
363 lines
10 KiB
Java
> 如果阅读时，发现错误，或者动画不可以显示的问题可以添加我微信好友 **[tan45du_one](https://raw.githubusercontent.com/tan45du/tan45du.github.io/master/个人微信.15egrcgqd94w.jpg)** ，备注 github + 题目 + 问题 向我反馈
|
||
>
|
||
> 感谢支持，该仓库会一直维护，希望对各位有一丢丢帮助。
|
||
>
|
||
> 另外希望手机阅读的同学可以来我的 <u>[**公众号：袁厨的算法小屋**](https://raw.githubusercontent.com/tan45du/test/master/微信图片_20210320152235.2pthdebvh1c0.png)</u> 两个平台同步，想要和题友一起刷题，互相监督的同学，可以在我的小屋点击<u>[**刷题小队**](https://raw.githubusercontent.com/tan45du/test/master/微信图片_20210320152235.2pthdebvh1c0.png)</u>进入。
|
||
|
||
### [59.螺旋矩阵 II](https://leetcode-cn.com/problems/spiral-matrix-ii)
|
||
|
||
给你一个正整数 `n` ，生成一个包含 `1` 到 `n2` 所有元素，且元素按顺时针顺序螺旋排列的 `n x n` 正方形矩阵 `matrix` 。
|
||
|
||
**示例 1：**
|
||
|
||
> 输入：n = 3
|
||
> 输出：[[1,2,3],[8,9,4],[7,6,5]]
|
||
|
||
**示例 2：**
|
||
|
||
> 输入：n = 1
|
||
> 输出：[[1]]
|
||
|
||
其实我们只要做过了螺旋矩阵 第一题，这个题目我们完全可以一下搞定，几乎没有进行更改，我们先来看下 **leetcode 54** 题的解析。
|
||
|
||
### leetcode 54 螺旋矩阵
|
||
|
||
题目描述
|
||
|
||
_给定一个包含 m_ x n 个元素的矩阵（m 行, n 列），请按照顺时针螺旋顺序，返回矩阵中的所有元素。
|
||
|
||
示例一
|
||
|
||
> 输入：matrix = [[1,2,3],[4,5,6],[7,8,9]]
|
||
> 输出：[1,2,3,6,9,8,7,4,5]
|
||
|
||
示例二
|
||
|
||
> 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]
|
||
|
||
这个题目很细非常细，思路很容易想到，但是要是完全实现也不是特别容易，我们一起分析下这个题目，我们可以这样理解，我们像剥洋葱似的一步步的剥掉外皮，直到遍历结束，见下图。
|
||
|
||
__
|
||
|
||
题目很容易理解，但是要想完全执行出来，也是不容易的，因为这里面的细节太多了，我们需要认真仔细的考虑边界。
|
||
|
||
我们也要考虑重复遍历的情况即什么时候跳出循环。刚才我们通过箭头知道了我们元素的遍历顺序，这个题目也就完成了一大半了，下面我们来讨论一下什么时候跳出循环，见下图。
|
||
|
||
注：这里需要注意的是，框框代表的是每个边界。
|
||
|
||
|
||
|
||
题目代码：
|
||
|
||
Java Code:
|
||
|
||
```java
|
||
class Solution {
|
||
public List<Integer> spiralOrder(int[][] matrix) {
|
||
|
||
List<Integer> arr = new ArrayList<>();
|
||
int left = 0, right = matrix[0].length-1;
|
||
int top = 0, down = matrix.length-1;
|
||
|
||
while (true) {
|
||
for (int i = left; i <= right; ++i) {
|
||
arr.add(matrix[top][i]);
|
||
}
|
||
top++;
|
||
if (top > down) break;
|
||
for (int i = top; i <= down; ++i) {
|
||
arr.add(matrix[i][right]);
|
||
}
|
||
right--;
|
||
if (left > right) break;
|
||
for (int i = right; i >= left; --i) {
|
||
arr.add(matrix[down][i]);
|
||
}
|
||
down--;
|
||
if (top > down) break;
|
||
for (int i = down; i >= top; --i) {
|
||
arr.add(matrix[i][left]);
|
||
}
|
||
left++;
|
||
if (left > right) break;
|
||
|
||
}
|
||
return arr;
|
||
}
|
||
}
|
||
|
||
```
|
||
|
||
Python3 Code:
|
||
|
||
```python
|
||
from typing import List
|
||
class Solution:
|
||
def spiralOrder(self, matrix: List[List[int]])->List[int]:
|
||
arr = []
|
||
left = 0
|
||
right = len(matrix[0]) - 1
|
||
top = 0
|
||
down = len(matrix) - 1
|
||
while True:
|
||
for i in range(left, right + 1):
|
||
arr.append(matrix[top][i])
|
||
top += 1
|
||
if top > down:
|
||
break
|
||
for i in range(top, down + 1):
|
||
arr.append(matrix[i][right])
|
||
right -= 1
|
||
if left > right:
|
||
break
|
||
for i in range(right, left - 1, -1):
|
||
arr.append(matrix[down][i])
|
||
down -= 1
|
||
if top > down:
|
||
break
|
||
for i in range(down, top - 1, -1):
|
||
arr.append(matrix[i][left])
|
||
left += 1
|
||
if left > right:
|
||
break
|
||
return arr
|
||
```
|
||
|
||
C++ Code:
|
||
|
||
```cpp
|
||
class Solution {
|
||
public:
|
||
vector<int> spiralOrder(vector<vector<int>>& matrix) {
|
||
vector <int> arr;
|
||
int left = 0, right = matrix[0].size()-1;
|
||
int top = 0, down = matrix.size()-1;
|
||
while (true) {
|
||
for (int i = left; i <= right; ++i) {
|
||
arr.emplace_back(matrix[top][i]);
|
||
}
|
||
top++;
|
||
if (top > down) break;
|
||
for (int i = top; i <= down; ++i) {
|
||
arr.emplace_back(matrix[i][right]);
|
||
}
|
||
right--;
|
||
if (left > right) break;
|
||
for (int i = right; i >= left; --i) {
|
||
arr.emplace_back(matrix[down][i]);
|
||
}
|
||
down--;
|
||
if (top > down) break;
|
||
for (int i = down; i >= top; --i) {
|
||
arr.emplace_back(matrix[i][left]);
|
||
}
|
||
left++;
|
||
if (left > right) break;
|
||
}
|
||
return arr;
|
||
}
|
||
};
|
||
```
|
||
|
||
Swift Code:
|
||
|
||
```swift
|
||
class Solution {
|
||
func spiralOrder(_ matrix: [[Int]]) -> [Int] {
|
||
var arr:[Int] = []
|
||
var left = 0, right = matrix[0].count - 1
|
||
var top = 0, down = matrix.count - 1
|
||
|
||
while (true) {
|
||
for i in left...right {
|
||
arr.append(matrix[top][i])
|
||
}
|
||
top += 1
|
||
if top > down { break }
|
||
for i in top...down {
|
||
arr.append(matrix[i][right])
|
||
}
|
||
right -= 1
|
||
if left > right { break}
|
||
for i in stride(from: right, through: left, by: -1) {
|
||
arr.append(matrix[down][i])
|
||
}
|
||
down -= 1
|
||
if top > down { break}
|
||
for i in stride(from: down, through: top, by: -1) {
|
||
arr.append(matrix[i][left])
|
||
}
|
||
left += 1
|
||
if left > right { break}
|
||
}
|
||
|
||
return arr
|
||
}
|
||
}
|
||
```
|
||
|
||
我们仅仅是将 54 反过来了，往螺旋矩阵里面插值，下面我们直接看代码吧,大家可以也可以对其改进，大家可以思考一下，如果修改能够让代码更简洁！
|
||
|
||
Java Code:
|
||
|
||
```java
|
||
class Solution {
|
||
public int[][] generateMatrix(int n) {
|
||
|
||
int[][] arr = new int[n][n];
|
||
int left = 0;
|
||
int right = n-1;
|
||
int top = 0;
|
||
int buttom = n-1;
|
||
int num = 1;
|
||
int numsize = n*n;
|
||
while (true) {
|
||
for (int i = left; i <= right; ++i) {
|
||
arr[top][i] = num++;
|
||
}
|
||
top++;
|
||
if (num > numsize) break;
|
||
for (int i = top; i <= buttom; ++i) {
|
||
arr[i][right] = num++;
|
||
|
||
}
|
||
right--;
|
||
if (num > numsize) break;
|
||
for (int i = right; i >= left; --i) {
|
||
arr[buttom][i] = num++;
|
||
}
|
||
buttom--;
|
||
if (num > numsize) break;
|
||
for (int i = buttom; i >= top; --i) {
|
||
arr[i][left] = num++;
|
||
}
|
||
left++;
|
||
if (num > numsize) break;
|
||
|
||
}
|
||
return arr;
|
||
}
|
||
}
|
||
```
|
||
|
||
Python3 Code:
|
||
|
||
```python
|
||
from typing import List
|
||
import numpy as np
|
||
class Solution:
|
||
def generateMatrix(self, n: int)->List[List[int]]:
|
||
arr = np.array([[0] * n] * n)
|
||
left = 0
|
||
right = n - 1
|
||
top = 0
|
||
buttom = n - 1
|
||
num = 1
|
||
numsize = n * n
|
||
while True:
|
||
for i in range(left, right + 1):
|
||
arr[top][i] = num
|
||
num += 1
|
||
top += 1
|
||
if num > numsize:
|
||
break
|
||
for i in range(top, buttom + 1):
|
||
arr[i][right] = num
|
||
num += 1
|
||
right -= 1
|
||
if num > numsize:
|
||
break
|
||
for i in range(right, left - 1, -1):
|
||
arr[buttom][i] = num
|
||
num += 1
|
||
buttom -= 1
|
||
if num > numsize:
|
||
break
|
||
for i in range(buttom, top - 1, -1):
|
||
arr[i][left] = num
|
||
num += 1
|
||
left += 1
|
||
if num > numsize:
|
||
break
|
||
return arr.tolist()
|
||
```
|
||
|
||
C++ Code:
|
||
|
||
```cpp
|
||
class Solution {
|
||
public:
|
||
vector<vector<int>> generateMatrix(int n) {
|
||
vector <vector <int>> arr(n, vector <int>(n));
|
||
int left = 0, right = n-1, top = 0, buttom = n - 1, num = 1, numsize = n * n;
|
||
while (true) {
|
||
for (int i = left; i <= right; ++i) {
|
||
arr[top][i] = num++;
|
||
}
|
||
top++;
|
||
if (num > numsize) break;
|
||
for (int i = top; i <= buttom; ++i) {
|
||
arr[i][right] = num++;
|
||
}
|
||
right--;
|
||
if (num > numsize) break;
|
||
for (int i = right; i >= left; --i) {
|
||
arr[buttom][i] = num++;
|
||
}
|
||
buttom--;
|
||
if (num > numsize) break;
|
||
for (int i = buttom; i >= top; --i) {
|
||
arr[i][left] = num++;
|
||
}
|
||
left++;
|
||
if (num > numsize) break;
|
||
|
||
}
|
||
return arr;
|
||
}
|
||
};
|
||
```
|
||
|
||
Swift Code:
|
||
|
||
```swift
|
||
class Solution {
|
||
func generateMatrix(_ n: Int) -> [[Int]] {
|
||
var arr:[[Int]] = Array.init(repeating: Array.init(repeating: 0, count: n), count: n)
|
||
var left = 0, right = n - 1
|
||
var top = 0, bottom = n - 1
|
||
var num = 1, numSize = n * n
|
||
|
||
while true {
|
||
for i in left...right {
|
||
arr[top][i] = num
|
||
num += 1
|
||
}
|
||
top += 1
|
||
if num > numSize { break}
|
||
for i in top...bottom {
|
||
arr[i][right] = num
|
||
num += 1
|
||
}
|
||
right -= 1
|
||
if num > numSize { break}
|
||
for i in stride(from: right, through: left, by: -1) {
|
||
arr[bottom][i] = num
|
||
num += 1
|
||
}
|
||
bottom -= 1
|
||
if num > numSize { break}
|
||
for i in stride(from: bottom, through: top, by: -1) {
|
||
arr[i][left] = num
|
||
num += 1
|
||
}
|
||
left += 1
|
||
if num > numSize { break}
|
||
}
|
||
|
||
return arr
|
||
}
|
||
}
|
||
```
|