Skip to content

Navigation Menu

Sign in
Appearance settings

Search code, repositories, users, issues, pull requests...

Provide feedback

We read every piece of feedback, and take your input very seriously.

Saved searches

Use saved searches to filter your results more quickly
Sign up
Appearance settings

Commit 25a4447

Browse files
committed
feat: add solutions to lc problem: No.0519
No.0519.Random Flip Matrix
1 parent d85b7a1 commit 25a4447

File tree

4 files changed

+165
-23
lines changed

4 files changed

+165
-23
lines changed

‎solution/0500-0599/0519.Random Flip Matrix/README.md‎

Lines changed: 55 additions & 3 deletions
Original file line numberDiff line numberDiff line change
@@ -36,7 +36,6 @@
3636

3737
<p>输入包含两个列表:被调用的子程序和他们的参数。<code>Solution</code> 的构造函数有两个参数,分别为 <code>n_rows</code> 和 <code>n_cols</code>。<code>flip</code>&nbsp;和 <code>reset</code> 没有参数,参数总会以列表形式给出,哪怕该列表为空</p>
3838

39-
4039
## 解法
4140

4241
<!-- 这里可写通用的实现逻辑 -->
@@ -48,15 +47,68 @@
4847
<!-- 这里可写当前语言的特殊实现逻辑 -->
4948

5049
```python
51-
50+
class Solution:
51+
52+
def __init__(self, m: int, n: int):
53+
self.m = m
54+
self.n = n
55+
self.total = m * n
56+
self.mp = {}
57+
58+
def flip(self) -> List[int]:
59+
self.total -= 1
60+
x = random.randint(0, self.total)
61+
idx = self.mp.get(x, x)
62+
self.mp[x] = self.mp.get(self.total, self.total)
63+
return [idx // self.n, idx % self.n]
64+
65+
def reset(self) -> None:
66+
self.total = self.m * self.n
67+
self.mp.clear()
68+
69+
# Your Solution object will be instantiated and called as such:
70+
# obj = Solution(m, n)
71+
# param_1 = obj.flip()
72+
# obj.reset()
5273
```
5374

5475
### **Java**
5576

5677
<!-- 这里可写当前语言的特殊实现逻辑 -->
5778

5879
```java
59-
80+
class Solution {
81+
private int m;
82+
private int n;
83+
private int total;
84+
private Random rand = new Random();
85+
private Map<Integer, Integer> mp = new HashMap<>();
86+
87+
public Solution(int m, int n) {
88+
this.m = m;
89+
this.n = n;
90+
this.total = m * n;
91+
}
92+
93+
public int[] flip() {
94+
int x = rand.nextInt(total--);
95+
int idx = mp.getOrDefault(x, x);
96+
mp.put(x, mp.getOrDefault(total, total));
97+
return new int[]{idx / n, idx % n};
98+
}
99+
100+
public void reset() {
101+
total = m * n;
102+
mp.clear();
103+
}
104+
}
105+
106+
/**
107+
* Your Solution object will be instantiated and called as such:
108+
* Solution obj = new Solution(m, n);
109+
* int[] param_1 = obj.flip();
110+
* obj.reset();
111+
*/
60112
```
61113

62114
### **...**

‎solution/0500-0599/0519.Random Flip Matrix/README_EN.md‎

Lines changed: 55 additions & 20 deletions
Original file line numberDiff line numberDiff line change
@@ -6,25 +6,17 @@
66

77
<p>You are given the number of rows <code>n_rows</code>&nbsp;and number of columns <code>n_cols</code>&nbsp;of a&nbsp;2D&nbsp;binary matrix&nbsp;where all values are initially 0.&nbsp;Write a function <code>flip</code>&nbsp;which chooses&nbsp;a 0 value&nbsp;<a href="https://en.wikipedia.org/wiki/Discrete_uniform_distribution" target="_blank">uniformly at random</a>,&nbsp;changes it to 1,&nbsp;and then returns the position <code>[row.id, col.id]</code> of that value. Also, write a function <code>reset</code> which sets all values back to 0.&nbsp;<strong>Try to minimize the number of calls to system&#39;s Math.random()</strong> and optimize the time and&nbsp;space complexity.</p>
88

9-
10-
119
<p>Note:</p>
1210

13-
14-
1511
<ol>
1612
<li><code>1 &lt;= n_rows, n_cols&nbsp;&lt;= 10000</code></li>
1713
<li><code>0 &lt;= row.id &lt; n_rows</code> and <code>0 &lt;= col.id &lt; n_cols</code></li>
1814
<li><code>flip</code>&nbsp;will not be called when the matrix has no&nbsp;0 values left.</li>
1915
<li>the total number of calls to&nbsp;<code>flip</code>&nbsp;and <code>reset</code>&nbsp;will not exceed&nbsp;1000.</li>
2016
</ol>
2117

22-
23-
2418
<p><strong>Example 1:</strong></p>
2519

26-
27-
2820
<pre>
2921

3022
<strong>Input:
@@ -37,14 +29,10 @@
3729

3830
</pre>
3931

40-
41-
4232
<div>
4333

4434
<p><strong>Example 2:</strong></p>
4535

46-
47-
4836
<pre>
4937

5038
<strong>Input:
@@ -57,30 +45,77 @@
5745

5846
</div>
5947

60-
61-
6248
<p><strong>Explanation of Input Syntax:</strong></p>
6349

64-
65-
6650
<p>The input is two lists:&nbsp;the subroutines called&nbsp;and their&nbsp;arguments. <code>Solution</code>&#39;s constructor&nbsp;has two arguments, <code>n_rows</code> and <code>n_cols</code>.&nbsp;<code>flip</code>&nbsp;and <code>reset</code> have&nbsp;no&nbsp;arguments.&nbsp;Arguments&nbsp;are&nbsp;always wrapped with a list, even if there aren&#39;t any.</p>
6751

68-
69-
7052
## Solutions
7153

7254
<!-- tabs:start -->
7355

7456
### **Python3**
7557

7658
```python
77-
59+
class Solution:
60+
61+
def __init__(self, m: int, n: int):
62+
self.m = m
63+
self.n = n
64+
self.total = m * n
65+
self.mp = {}
66+
67+
def flip(self) -> List[int]:
68+
self.total -= 1
69+
x = random.randint(0, self.total)
70+
idx = self.mp.get(x, x)
71+
self.mp[x] = self.mp.get(self.total, self.total)
72+
return [idx // self.n, idx % self.n]
73+
74+
def reset(self) -> None:
75+
self.total = self.m * self.n
76+
self.mp.clear()
77+
78+
# Your Solution object will be instantiated and called as such:
79+
# obj = Solution(m, n)
80+
# param_1 = obj.flip()
81+
# obj.reset()
7882
```
7983

8084
### **Java**
8185

8286
```java
83-
87+
class Solution {
88+
private int m;
89+
private int n;
90+
private int total;
91+
private Random rand = new Random();
92+
private Map<Integer, Integer> mp = new HashMap<>();
93+
94+
public Solution(int m, int n) {
95+
this.m = m;
96+
this.n = n;
97+
this.total = m * n;
98+
}
99+
100+
public int[] flip() {
101+
int x = rand.nextInt(total--);
102+
int idx = mp.getOrDefault(x, x);
103+
mp.put(x, mp.getOrDefault(total, total));
104+
return new int[]{idx / n, idx % n};
105+
}
106+
107+
public void reset() {
108+
total = m * n;
109+
mp.clear();
110+
}
111+
}
112+
113+
/**
114+
* Your Solution object will be instantiated and called as such:
115+
* Solution obj = new Solution(m, n);
116+
* int[] param_1 = obj.flip();
117+
* obj.reset();
118+
*/
84119
```
85120

86121
### **...**
Lines changed: 32 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,32 @@
1+
class Solution {
2+
private int m;
3+
private int n;
4+
private int total;
5+
private Random rand = new Random();
6+
private Map<Integer, Integer> mp = new HashMap<>();
7+
8+
public Solution(int m, int n) {
9+
this.m = m;
10+
this.n = n;
11+
this.total = m * n;
12+
}
13+
14+
public int[] flip() {
15+
int x = rand.nextInt(total--);
16+
int idx = mp.getOrDefault(x, x);
17+
mp.put(x, mp.getOrDefault(total, total));
18+
return new int[]{idx / n, idx % n};
19+
}
20+
21+
public void reset() {
22+
total = m * n;
23+
mp.clear();
24+
}
25+
}
26+
27+
/**
28+
* Your Solution object will be instantiated and called as such:
29+
* Solution obj = new Solution(m, n);
30+
* int[] param_1 = obj.flip();
31+
* obj.reset();
32+
*/
Lines changed: 23 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,23 @@
1+
class Solution:
2+
3+
def __init__(self, m: int, n: int):
4+
self.m = m
5+
self.n = n
6+
self.total = m * n
7+
self.mp = {}
8+
9+
def flip(self) -> List[int]:
10+
self.total -= 1
11+
x = random.randint(0, self.total)
12+
idx = self.mp.get(x, x)
13+
self.mp[x] = self.mp.get(self.total, self.total)
14+
return [idx // self.n, idx % self.n]
15+
16+
def reset(self) -> None:
17+
self.total = self.m * self.n
18+
self.mp.clear()
19+
20+
# Your Solution object will be instantiated and called as such:
21+
# obj = Solution(m, n)
22+
# param_1 = obj.flip()
23+
# obj.reset()

0 commit comments

Comments
(0)

AltStyle によって変換されたページ (->オリジナル) /