🤖 Daily Challenge: Problem #762

SOLVED.md

@@ -91,6 +91,7 @@
 | 744 | [Find Smallest Letter Greater Than Target](https://leetcode.com/problems/find-smallest-letter-greater-than-target/) | [Code](src/leetcode/problems/find-smallest-letter-greater-than-target.cpp) / [Test](test/leetcode/problems/find-smallest-letter-greater-than-target.cpp) |
 | 756 | [Pyramid Transition Matrix](https://leetcode.com/problems/pyramid-transition-matrix/) | [Code](src/leetcode/problems/pyramid-transition-matrix.cpp) / [Test](test/leetcode/problems/pyramid-transition-matrix.cpp) |
 | 761 | [Special Binary String](https://leetcode.com/problems/special-binary-string/) | [Code](src/leetcode/problems/special-binary-string.cpp) / [Test](test/leetcode/problems/special-binary-string.cpp) |
+| 762 | [Prime Number of Set Bits in Binary Representation](https://leetcode.com/problems/prime-number-of-set-bits-in-binary-representation/) | [Code](src/leetcode/problems/prime-number-of-set-bits-in-binary-representation.cpp) / [Test](test/leetcode/problems/prime-number-of-set-bits-in-binary-representation.cpp) |
 | 799 | [Champagne Tower](https://leetcode.com/problems/champagne-tower/) | [Code](src/leetcode/problems/champagne-tower.cpp) / [Test](test/leetcode/problems/champagne-tower.cpp) |
 | 816 | [Ambiguous Coordinates](https://leetcode.com/problems/ambiguous-coordinates/) | [Code](src/leetcode/problems/ambiguous-coordinates.cpp) / [Test](test/leetcode/problems/ambiguous-coordinates.cpp) |
 | 829 | [Consecutive Numbers Sum](https://leetcode.com/problems/consecutive-numbers-sum/) | [Code](src/leetcode/problems/consecutive-numbers-sum.cpp) / [Test](test/leetcode/problems/consecutive-numbers-sum.cpp) |

include/leetcode/problems/prime-number-of-set-bits-in-binary-representation.h

@@ -0,0 +1,19 @@
+
+#include "leetcode/core.h"
+
+namespace leetcode {
+namespace problem_762 {
+
+using Func = std::function<int(int, int)>;
+
+class PrimeNumberOfSetBitsInBinaryRepresentationSolution : public SolutionBase<Func> {
+ public:
+  //! 762. Prime Number of Set Bits in Binary Representation
+  //! https://leetcode.com/problems/prime-number-of-set-bits-in-binary-representation/
+  int countPrimeSetBits(int left, int right);
+
+  PrimeNumberOfSetBitsInBinaryRepresentationSolution();
+};
+
+}  // namespace problem_762
+}  // namespace leetcode

src/leetcode/problems/prime-number-of-set-bits-in-binary-representation.cpp

@@ -0,0 +1,80 @@
+
+#include "leetcode/problems/prime-number-of-set-bits-in-binary-representation.h"
+
+namespace leetcode {
+namespace problem_762 {
+
+// 判断是否为素数（只处理小数字，因为 set bits 最多约 20 个）
+static bool isPrime(int n) {
+  if (n < 2) return false;
+  if (n == 2) return true;
+  if (n % 2 == 0) return false;
+  for (int i = 3; i * i <= n; i += 2) {
+    if (n % i == 0) return false;
+  }
+  return true;
+}
+
+// 遍历每个数字，统计二进制中素数个 1 的数字个数
+// 时间复杂度: O((right - left + 1) * log(right))，空间复杂度: O(1)
+static int solution1(int left, int right) {
+  int count = 0;
+  for (int num = left; num <= right; ++num) {
+    int setBits = __builtin_popcount(num);
+    if (isPrime(setBits)) {
+      ++count;
+    }
+  }
+  return count;
+}
+
+// 使用位运算优化版本
+// 时间复杂度: O((right - left + 1) * log(right))，空间复杂度: O(1)
+static int solution2(int left, int right) {
+  int count = 0;
+  for (int num = left; num <= right; ++num) {
+    int n = num;
+    int setBits = 0;
+    while (n) {
+      setBits += (n & 1);
+      n >>= 1;
+    }
+    if (isPrime(setBits)) {
+      ++count;
+    }
+  }
+  return count;
+}
+
+// 使用打表优化素数判断（set bits 最多约 20 个）
+// 时间复杂度: O(right - left + 1)，空间复杂度: O(1)
+static int solution3(int left, int right) {
+  // 1-20 中的素数集合：2, 3, 5, 7, 11, 13, 17, 19
+  // 使用位掩码表示：第 i 位为 1 表示 i 是素数
+  const int primeMask = (1 << 2) | (1 << 3) | (1 << 5) | (1 << 7) | 
+                        (1 << 11) | (1 << 13) | (1 << 17) | (1 << 19);
+  int count = 0;
+  for (int num = left; num <= right; ++num) {
+    int setBits = __builtin_popcount(num);
+    if (primeMask & (1 << setBits)) {
+      ++count;
+    }
+  }
+  return count;
+}
+
+PrimeNumberOfSetBitsInBinaryRepresentationSolution::PrimeNumberOfSetBitsInBinaryRepresentationSolution() {
+  setMetaInfo({.id = 762,
+               .title = "Prime Number of Set Bits in Binary Representation",
+               .url = "https://leetcode.com/problems/prime-number-of-set-bits-in-binary-representation/"});
+  registerStrategy("Builtin Popcount", solution1);
+  registerStrategy("Bit Manipulation", solution2);
+  registerStrategy("Prime Mask", solution3);
+}
+
+int PrimeNumberOfSetBitsInBinaryRepresentationSolution::countPrimeSetBits(int left, int right) {
+  return getSolution()(left, right);
+}
+
+}  // namespace problem_762
+}  // namespace leetcode

test/leetcode/problems/prime-number-of-set-bits-in-binary-representation.cpp

@@ -0,0 +1,66 @@
+
+#include "leetcode/problems/prime-number-of-set-bits-in-binary-representation.h"
+
+#include "gtest/gtest.h"
+
+namespace leetcode {
+namespace problem_762 {
+
+class PrimeNumberOfSetBitsInBinaryRepresentationTest : public ::testing::TestWithParam<std::string> {
+ protected:
+  void SetUp() override { solution.setStrategy(GetParam()); }
+
+  PrimeNumberOfSetBitsInBinaryRepresentationSolution solution;
+};
+
+TEST_P(PrimeNumberOfSetBitsInBinaryRepresentationTest, Example1) {
+  int left = 6;
+  int right = 10;
+  int expected = 4;
+  EXPECT_EQ(expected, solution.countPrimeSetBits(left, right));
+}
+
+TEST_P(PrimeNumberOfSetBitsInBinaryRepresentationTest, Example2) {
+  int left = 10;
+  int right = 15;
+  int expected = 5;
+  EXPECT_EQ(expected, solution.countPrimeSetBits(left, right));
+}
+
+TEST_P(PrimeNumberOfSetBitsInBinaryRepresentationTest, SingleNumber) {
+  int left = 7;
+  int right = 7;
+  // 7 -> 111, 3 set bits, 3 is prime
+  int expected = 1;
+  EXPECT_EQ(expected, solution.countPrimeSetBits(left, right));
+}
+
+TEST_P(PrimeNumberOfSetBitsInBinaryRepresentationTest, RangeWithNoPrimeSetBits) {
+  int left = 1;
+  int right = 1;
+  // 1 -> 1, 1 set bit, 1 is not prime
+  int expected = 0;
+  EXPECT_EQ(expected, solution.countPrimeSetBits(left, right));
+}
+
+TEST_P(PrimeNumberOfSetBitsInBinaryRepresentationTest, PowerOfTwo) {
+  int left = 1;
+  int right = 8;
+  // 1 -> 1 (not prime)
+  // 2 -> 10 (1, not prime)
+  // 3 -> 11 (2, prime)
+  // 4 -> 100 (1, not prime)
+  // 5 -> 101 (2, prime)
+  // 6 -> 110 (2, prime)
+  // 7 -> 111 (3, prime)
+  // 8 -> 1000 (1, not prime)
+  int expected = 4;
+  EXPECT_EQ(expected, solution.countPrimeSetBits(left, right));
+}
+
+INSTANTIATE_TEST_SUITE_P(
+    LeetCode, PrimeNumberOfSetBitsInBinaryRepresentationTest,
+    ::testing::ValuesIn(PrimeNumberOfSetBitsInBinaryRepresentationSolution().getStrategyNames()));
+
+}  // namespace problem_762
+}  // namespace leetcode