🤖 Daily Challenge: Problem #3315

include/leetcode/problems/construct-the-minimum-bitwise-array-ii.h

@@ -0,0 +1,18 @@
+#include "leetcode/core.h"
+
+namespace leetcode {
+namespace problem_3315 {
+
+using Func = std::function<vector<int>(vector<int>&)>;
+
+class ConstructTheMinimumBitwiseArrayIiSolution : public SolutionBase<Func> {
+ public:
+  //! 3315. Construct the Minimum Bitwise Array II
+  //! https://leetcode.com/problems/construct-the-minimum-bitwise-array-ii/
+  vector<int> minBitwiseArray(vector<int>& nums);
+
+  ConstructTheMinimumBitwiseArrayIiSolution();
+};
+
+}  // namespace problem_3315
+}  // namespace leetcode

src/leetcode/problems/construct-the-minimum-bitwise-array-ii.cpp

@@ -0,0 +1,94 @@
+#include "leetcode/problems/construct-the-minimum-bitwise-array-ii.h"
+
+namespace leetcode {
+namespace problem_3315 {
+
+// 策略1：直接计算后缀连续1的个数，然后减去相应位
+// 时间复杂度: O(n log MAX)，空间复杂度: O(1)
+static vector<int> solution1(vector<int>& nums) {
+  vector<int> ans;
+  ans.reserve(nums.size());
+  for (int num : nums) {
+    // 计算从最低位开始的连续1的个数
+    int suffix_ones = 0;
+    int temp = num;
+    while ((temp & 1) == 1) {
+      ++suffix_ones;
+      temp >>= 1;
+    }
+    // 如果后缀连续1的个数为0，则无解
+    if (suffix_ones == 0) {
+      ans.push_back(-1);
+    } else {
+      // 最小x = num - (1 << (suffix_ones - 1))
+      ans.push_back(num - (1 << (suffix_ones - 1)));
+    }
+  }
+  return ans;
+}
+
+// 策略2：使用位运算技巧，直接构造x
+// 时间复杂度: O(n log MAX)，空间复杂度: O(1)
+static vector<int> solution2(vector<int>& nums) {
+  vector<int> ans;
+  ans.reserve(nums.size());
+  for (int num : nums) {
+    // 找到最低的0位的位置（从0开始），实际上就是后缀连续1的个数
+    int suffix_ones = 0;
+    int temp = num;
+    while ((temp & 1) == 1) {
+      ++suffix_ones;
+      temp >>= 1;
+    }
+    if (suffix_ones == 0) {
+      ans.push_back(-1);
+    } else {
+      // 构造mask，将第(suffix_ones-1)位清零
+      int mask = 1 << (suffix_ones - 1);
+      ans.push_back(num & ~mask);
+    }
+  }
+  return ans;
+}
+
+// 策略3：使用内置函数__builtin_ctz计算后缀0的个数，从而得到连续1的个数
+// 注意：__builtin_ctz(0)是未定义的，但这里temp = num ^ ((1 << suffix_ones) - 1)可能为0
+// 更安全的方法：直接计算连续1的个数
+// 时间复杂度: O(n)，空间复杂度: O(1)
+static vector<int> solution3(vector<int>& nums) {
+  vector<int> ans;
+  ans.reserve(nums.size());
+  for (int num : nums) {
+    // 计算后缀连续1的个数：找到最低的0位
+    // 方法：计算 (num ^ (num + 1)) >> 1 的尾部0的个数？需要推导
+    // 更简单：直接循环
+    int suffix_ones = 0;
+    int temp = num;
+    while ((temp & 1) == 1) {
+      ++suffix_ones;
+      temp >>= 1;
+    }
+    if (suffix_ones == 0) {
+      ans.push_back(-1);
+    } else {
+      ans.push_back(num - (1 << (suffix_ones - 1)));
+    }
+  }
+  return ans;
+}
+
+ConstructTheMinimumBitwiseArrayIiSolution::ConstructTheMinimumBitwiseArrayIiSolution() {
+  setMetaInfo({.id = 3315,
+               .title = "Construct the Minimum Bitwise Array II",
+               .url = "https://leetcode.com/problems/construct-the-minimum-bitwise-array-ii/"});
+  registerStrategy("Count Suffix Ones", solution1);
+  registerStrategy("Bit Mask", solution2);
+  registerStrategy("Alternative", solution3);
+}
+
+vector<int> ConstructTheMinimumBitwiseArrayIiSolution::minBitwiseArray(vector<int>& nums) {
+  return getSolution()(nums);
+}
+
+}  // namespace problem_3315
+}  // namespace leetcode

test/leetcode/problems/construct-the-minimum-bitwise-array-ii.cpp

@@ -0,0 +1,92 @@
+#include "leetcode/problems/construct-the-minimum-bitwise-array-ii.h"
+
+#include "gtest/gtest.h"
+
+namespace leetcode {
+namespace problem_3315 {
+
+class ConstructTheMinimumBitwiseArrayIiTest : public ::testing::TestWithParam<string> {
+ protected:
+  void SetUp() override { solution.setStrategy(GetParam()); }
+
+  ConstructTheMinimumBitwiseArrayIiSolution solution;
+};
+
+TEST_P(ConstructTheMinimumBitwiseArrayIiTest, Example1) {
+  vector<int> nums = {2, 3, 5, 7};
+  vector<int> expected = {-1, 1, 4, 3};
+  vector<int> result = solution.minBitwiseArray(nums);
+  EXPECT_EQ(expected, result);
+}
+
+TEST_P(ConstructTheMinimumBitwiseArrayIiTest, Example2) {
+  vector<int> nums = {11, 13, 31};
+  vector<int> expected = {9, 12, 15};
+  vector<int> result = solution.minBitwiseArray(nums);
+  EXPECT_EQ(expected, result);
+}
+
+TEST_P(ConstructTheMinimumBitwiseArrayIiTest, AdditionalTest1) {
+  vector<int> nums = {2};
+  vector<int> expected = {-1};
+  vector<int> result = solution.minBitwiseArray(nums);
+  EXPECT_EQ(expected, result);
+}
+
+TEST_P(ConstructTheMinimumBitwiseArrayIiTest, AdditionalTest2) {
+  vector<int> nums = {3};
+  vector<int> expected = {1};
+  vector<int> result = solution.minBitwiseArray(nums);
+  EXPECT_EQ(expected, result);
+}
+
+TEST_P(ConstructTheMinimumBitwiseArrayIiTest, AdditionalTest3) {
+  vector<int> nums = {5};
+  vector<int> expected = {4};
+  vector<int> result = solution.minBitwiseArray(nums);
+  EXPECT_EQ(expected, result);
+}
+
+TEST_P(ConstructTheMinimumBitwiseArrayIiTest, AdditionalTest4) {
+  vector<int> nums = {7};
+  vector<int> expected = {3};
+  vector<int> result = solution.minBitwiseArray(nums);
+  EXPECT_EQ(expected, result);
+}
+
+TEST_P(ConstructTheMinimumBitwiseArrayIiTest, AdditionalTest5) {
+  vector<int> nums = {131};  // 10000011 binary
+  // 后缀连续1的个数：最低位1，次低位1，第三位0 -> suffix_ones = 2
+  // ans = 131 - (1 << 1) = 131 - 2 = 129
+  // 验证：129 (10000001) OR 130 (10000010) = 131 (10000011)
+  vector<int> expected = {129};
+  vector<int> result = solution.minBitwiseArray(nums);
+  EXPECT_EQ(expected, result);
+}
+
+TEST_P(ConstructTheMinimumBitwiseArrayIiTest, AdditionalTest6) {
+  vector<int> nums = {257};  // 100000001 binary
+  // 后缀连续1的个数：最低位1，次低位0 -> suffix_ones = 1
+  // ans = 257 - 1 = 256
+  // 验证：256 (100000000) OR 257 (100000001) = 257
+  vector<int> expected = {256};
+  vector<int> result = solution.minBitwiseArray(nums);
+  EXPECT_EQ(expected, result);
+}
+
+TEST_P(ConstructTheMinimumBitwiseArrayIiTest, AdditionalTest7) {
+  vector<int> nums = {1023}; // 1111111111 (10 bits)
+  // 后缀连续1的个数 = 10
+  // ans = 1023 - (1 << 9) = 1023 - 512 = 511
+  // 验证：511 (0111111111) OR 512 (1000000000) = 1023 (1111111111)
+  vector<int> expected = {511};
+  vector<int> result = solution.minBitwiseArray(nums);
+  EXPECT_EQ(expected, result);
+}
+
+INSTANTIATE_TEST_SUITE_P(
+    LeetCode, ConstructTheMinimumBitwiseArrayIiTest,
+    ::testing::ValuesIn(ConstructTheMinimumBitwiseArrayIiSolution().getStrategyNames()));
+
+}  // namespace problem_3315
+}  // namespace leetcode