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feat: add solutions to lc problem: No.0672
No.0672.Bulb Switcher II
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‎solution/0600-0699/0672.Bulb Switcher II/README.md

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<!-- 这里可写通用的实现逻辑 -->
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**方法一：位运算**
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观察灯泡开关随按钮操作的变化规律，我们可以发现，位置 $i$ 与 $i+6$ 的灯泡，开关状态始终保持一致，因此，我们只需要考虑最多前 $n=6$ 个灯泡的开关状态。
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另外，对于每个按钮，若操作偶数次，相当于没执行操作；若操作奇数次，相当于操作了 $1$ 次。同时，不同按钮操作的先后顺序，也不影响结果。
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题目有 $4$ 个按钮，每个按钮有“操作偶数次”和“操作奇数次”两种状态，因此总共有 $2^4$ 种按钮状态。
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二进制枚举按钮的状态 `mask`，若当前状态满足题目 `presses` 的限制，我们可以通过位运算，模拟操作对应按钮，最终得到灯泡的状态 $t$，去重后的 $t$ 的数量就是答案。
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时空复杂度均为常数级别。
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<!-- tabs:start -->
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### **Python3**
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<!-- 这里可写当前语言的特殊实现逻辑 -->
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```python
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class Solution:
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def flipLights(self, n: int, presses: int) -> int:
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ops = (0b111111, 0b010101, 0b101010, 0b100100)
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n = min(n, 6)
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vis = set()
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for mask in range(1 << 4):
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cnt = mask.bit_count()
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if cnt <= presses and cnt % 2 == presses % 2:
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t = 0
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for i, op in enumerate(ops):
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if (mask >> i) & 1:
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t ^= op
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t &= (1 << 6) - 1
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t >>= 6 - n
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vis.add(t)
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return len(vis)
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```
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### **Java**
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<!-- 这里可写当前语言的特殊实现逻辑 -->
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```java
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class Solution {
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public int flipLights(int n, int presses) {
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int[] ops = new int[] {0b111111, 0b010101, 0b101010, 0b100100};
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Set<Integer> vis = new HashSet<>();
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n = Math.min(n, 6);
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for (int mask = 0; mask < 1 << 4; ++mask) {
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int cnt = Integer.bitCount(mask);
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if (cnt <= presses && cnt % 2 == presses % 2) {
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int t = 0;
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for (int i = 0; i < 4; ++i) {
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if (((mask >> i) & 1) == 1) {
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t ^= ops[i];
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}
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}
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t &= ((1 << 6) - 1);
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t >>= (6 - n);
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vis.add(t);
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}
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}
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return vis.size();
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}
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}
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```
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### **C++**
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```cpp
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class Solution {
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public:
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int flipLights(int n, int presses) {
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n = min(n, 6);
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vector<int> ops = {0b111111, 0b010101, 0b101010, 0b100100};
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unordered_set<int> vis;
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for (int mask = 0; mask < 1 << 4; ++mask) {
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int cnt = __builtin_popcount(mask);
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if (cnt > presses || cnt % 2 != presses % 2) continue;
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int t = 0;
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for (int i = 0; i < 4; ++i) {
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if (mask >> i & 1) {
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t ^= ops[i];
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}
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}
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t &= (1 << 6) - 1;
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t >>= (6 - n);
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vis.insert(t);
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}
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return vis.size();
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}
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};
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```
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### **Go**
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```go
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func flipLights(n int, presses int) int {
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if n > 6 {
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n = 6
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}
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ops := []int{0b111111, 0b010101, 0b101010, 0b100100}
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vis := map[int]bool{}
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for mask := 0; mask < 1<<4; mask++ {
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cnt := bits.OnesCount(uint(mask))
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if cnt <= presses && cnt%2 == presses%2 {
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t := 0
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for i, op := range ops {
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if mask>>i&1 == 1 {
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t ^= op
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}
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}
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t &= 1<<6 - 1
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t >>= (6 - n)
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vis[t] = true
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}
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}
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return len(vis)
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}
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```
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### **...**

‎solution/0600-0699/0672.Bulb Switcher II/README_EN.md

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### **Python3**
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```python
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class Solution:
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def flipLights(self, n: int, presses: int) -> int:
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ops = (0b111111, 0b010101, 0b101010, 0b100100)
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n = min(n, 6)
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vis = set()
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for mask in range(1 << 4):
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cnt = mask.bit_count()
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if cnt <= presses and cnt % 2 == presses % 2:
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t = 0
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for i, op in enumerate(ops):
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if (mask >> i) & 1:
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t ^= op
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t &= (1 << 6) - 1
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t >>= 6 - n
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vis.add(t)
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return len(vis)
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```
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### **Java**
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```java
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class Solution {
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public int flipLights(int n, int presses) {
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int[] ops = new int[] {0b111111, 0b010101, 0b101010, 0b100100};
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Set<Integer> vis = new HashSet<>();
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n = Math.min(n, 6);
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for (int mask = 0; mask < 1 << 4; ++mask) {
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int cnt = Integer.bitCount(mask);
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if (cnt <= presses && cnt % 2 == presses % 2) {
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int t = 0;
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for (int i = 0; i < 4; ++i) {
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if (((mask >> i) & 1) == 1) {
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t ^= ops[i];
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}
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}
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t &= ((1 << 6) - 1);
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t >>= (6 - n);
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vis.add(t);
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}
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}
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return vis.size();
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}
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}
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```
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### **C++**
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```cpp
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class Solution {
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public:
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int flipLights(int n, int presses) {
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n = min(n, 6);
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vector<int> ops = {0b111111, 0b010101, 0b101010, 0b100100};
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unordered_set<int> vis;
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for (int mask = 0; mask < 1 << 4; ++mask) {
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int cnt = __builtin_popcount(mask);
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if (cnt > presses || cnt % 2 != presses % 2) continue;
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int t = 0;
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for (int i = 0; i < 4; ++i) {
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if (mask >> i & 1) {
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t ^= ops[i];
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}
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}
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t &= (1 << 6) - 1;
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t >>= (6 - n);
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vis.insert(t);
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}
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return vis.size();
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}
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};
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```
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### **Go**
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```go
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func flipLights(n int, presses int) int {
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if n > 6 {
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n = 6
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}
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ops := []int{0b111111, 0b010101, 0b101010, 0b100100}
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vis := map[int]bool{}
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for mask := 0; mask < 1<<4; mask++ {
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cnt := bits.OnesCount(uint(mask))
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if cnt <= presses && cnt%2 == presses%2 {
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t := 0
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for i, op := range ops {
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if mask>>i&1 == 1 {
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t ^= op
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}
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}
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t &= 1<<6 - 1
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t >>= (6 - n)
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vis[t] = true
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}
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}
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return len(vis)
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}
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```
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### **...**

‎solution/0600-0699/0672.Bulb Switcher II/Solution.cpp

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class Solution {
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public:
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int flipLights(int n, int presses) {
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n = min(n, 6);
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vector<int> ops = {0b111111, 0b010101, 0b101010, 0b100100};
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unordered_set<int> vis;
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for (int mask = 0; mask < 1 << 4; ++mask) {
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int cnt = __builtin_popcount(mask);
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if (cnt > presses || cnt % 2 != presses % 2) continue;
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int t = 0;
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for (int i = 0; i < 4; ++i) {
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if (mask >> i & 1) {
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t ^= ops[i];
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}
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}
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t &= (1 << 6) - 1;
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t >>= (6 - n);
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vis.insert(t);
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}
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return vis.size();
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}
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};

‎solution/0600-0699/0672.Bulb Switcher II/Solution.go

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func flipLights(n int, presses int) int {
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if n > 6 {
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n = 6
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}
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ops := []int{0b111111, 0b010101, 0b101010, 0b100100}
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vis := map[int]bool{}
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for mask := 0; mask < 1<<4; mask++ {
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cnt := bits.OnesCount(uint(mask))
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if cnt <= presses && cnt%2 == presses%2 {
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t := 0
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for i, op := range ops {
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if mask>>i&1 == 1 {
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t ^= op
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}
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}
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t &= 1<<6 - 1
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t >>= (6 - n)
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vis[t] = true
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}
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}
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return len(vis)
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}

‎solution/0600-0699/0672.Bulb Switcher II/Solution.java

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class Solution {
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public int flipLights(int n, int presses) {
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int[] ops = new int[] {0b111111, 0b010101, 0b101010, 0b100100};
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Set<Integer> vis = new HashSet<>();
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n = Math.min(n, 6);
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for (int mask = 0; mask < 1 << 4; ++mask) {
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int cnt = Integer.bitCount(mask);
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if (cnt <= presses && cnt % 2 == presses % 2) {
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int t = 0;
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for (int i = 0; i < 4; ++i) {
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if (((mask >> i) & 1) == 1) {
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t ^= ops[i];
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}
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}
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t &= ((1 << 6) - 1);
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t >>= (6 - n);
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vis.add(t);
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}
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}
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return vis.size();
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}
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}

‎solution/0600-0699/0672.Bulb Switcher II/Solution.py

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class Solution:
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def flipLights(self, n: int, presses: int) -> int:
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ops = (0b111111, 0b010101, 0b101010, 0b100100)
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n = min(n, 6)
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vis = set()
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for mask in range(1 << 4):
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cnt = mask.bit_count()
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if cnt <= presses and cnt % 2 == presses % 2:
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t = 0
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for i, op in enumerate(ops):
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if (mask >> i) & 1:
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t ^= op
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t &= (1 << 6) - 1
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t >>= 6 - n
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vis.add(t)
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return len(vis)

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