feat: Add solution for LeetCode #868

Author: 0xMashiro

SOLVED.md

@@ -101,6 +101,7 @@
 | 848 | [Shifting Letters](https://leetcode.com/problems/shifting-letters/) | [Code](src/leetcode/problems/shifting-letters.cpp) / [Test](test/leetcode/problems/shifting-letters.cpp) |
 | 865 | [Smallest Subtree with all the Deepest Nodes](https://leetcode.com/problems/smallest-subtree-with-all-the-deepest-nodes/) | [Code](src/leetcode/problems/smallest-subtree-with-all-the-deepest-nodes.cpp) / [Test](test/leetcode/problems/smallest-subtree-with-all-the-deepest-nodes.cpp) |
 | 867 | [Transpose Matrix](https://leetcode.com/problems/transpose-matrix/) | [Code](src/leetcode/problems/transpose-matrix.cpp) / [Test](test/leetcode/problems/transpose-matrix.cpp) |
+| 868 | [Binary Gap](https://leetcode.com/problems/binary-gap/) | [Code](src/leetcode/problems/binary-gap.cpp) / [Test](test/leetcode/problems/binary-gap.cpp) |
 | 897 | [Increasing Order Search Tree](https://leetcode.com/problems/increasing-order-search-tree/) | [Code](src/leetcode/problems/increasing-order-search-tree.cpp) / [Test](test/leetcode/problems/increasing-order-search-tree.cpp) |
 | 898 | [Bitwise ORs of Subarrays](https://leetcode.com/problems/bitwise-ors-of-subarrays/) | [Code](src/leetcode/problems/bitwise-ors-of-subarrays.cpp) / [Test](test/leetcode/problems/bitwise-ors-of-subarrays.cpp) |
 | 915 | [Partition Array into Disjoint Intervals](https://leetcode.com/problems/partition-array-into-disjoint-intervals/) | [Code](src/leetcode/problems/partition-array-into-disjoint-intervals.cpp) / [Test](test/leetcode/problems/partition-array-into-disjoint-intervals.cpp) |

include/leetcode/problems/binary-gap.h

@@ -0,0 +1,18 @@
+#include "leetcode/core.h"
+
+namespace leetcode {
+namespace problem_868 {
+
+using Func = std::function<int(int)>;
+
+class BinaryGapSolution : public SolutionBase<Func> {
+ public:
+  //! 868. Binary Gap
+  //! https://leetcode.com/problems/binary-gap/
+  int binaryGap(int n);
+
+  BinaryGapSolution();
+};
+
+}  // namespace problem_868
+}  // namespace leetcode

src/leetcode/problems/binary-gap.cpp

@@ -0,0 +1,41 @@
+#include "leetcode/problems/binary-gap.h"
+
+namespace leetcode {
+namespace problem_868 {
+
+// 位运算扫描：从低位到高位遍历，记录上一个1的位置
+// 时间复杂度: O(log n), 空间复杂度: O(1)
+static int solution(int n) {
+  int lastPos = -1;  // 上一个1的位置
+  int maxDist = 0;   // 最大距离
+  int pos = 0;       // 当前位位置
+
+  while (n > 0) {
+    // 检查当前最低位是否为1
+    if (n & 1) {
+      if (lastPos != -1) {
+        // 计算与上一个1的距离
+        maxDist = max(maxDist, pos - lastPos);
+      }
+      lastPos = pos;  // 更新上一个1的位置
+    }
+    n >>= 1;  // 右移一位
+    ++pos;
+  }
+
+  return maxDist;
+}
+
+BinaryGapSolution::BinaryGapSolution() {
+  setMetaInfo({.id = 868,
+               .title = "Binary Gap",
+               .url = "https://leetcode.com/problems/binary-gap/"});
+  registerStrategy("Bit Scan", solution);
+}
+
+int BinaryGapSolution::binaryGap(int n) {
+  return getSolution()(n);
+}
+
+}  // namespace problem_868
+}  // namespace leetcode

test/leetcode/problems/binary-gap.cpp

@@ -0,0 +1,50 @@
+#include "leetcode/problems/binary-gap.h"
+
+#include "gtest/gtest.h"
+
+namespace leetcode {
+namespace problem_868 {
+
+class BinaryGapTest : public ::testing::TestWithParam<std::string> {
+ protected:
+  void SetUp() override { solution.setStrategy(GetParam()); }
+
+  BinaryGapSolution solution;
+};
+
+TEST_P(BinaryGapTest, Example1) {
+  // n = 22, binary = "10110"
+  EXPECT_EQ(2, solution.binaryGap(22));
+}
+
+TEST_P(BinaryGapTest, Example2) {
+  // n = 8, binary = "1000"
+  EXPECT_EQ(0, solution.binaryGap(8));
+}
+
+TEST_P(BinaryGapTest, Example3) {
+  // n = 5, binary = "101"
+  EXPECT_EQ(2, solution.binaryGap(5));
+}
+
+TEST_P(BinaryGapTest, SingleBit) {
+  // n = 1, binary = "1"
+  EXPECT_EQ(0, solution.binaryGap(1));
+}
+
+TEST_P(BinaryGapTest, AllOnes) {
+  // n = 15, binary = "1111", adjacent pairs: (0,1), (1,2), (2,3) all distance 1
+  EXPECT_EQ(1, solution.binaryGap(15));
+}
+
+TEST_P(BinaryGapTest, LargeGap) {
+  // n = 33, binary = "100001", gap = 5
+  EXPECT_EQ(5, solution.binaryGap(33));
+}
+
+INSTANTIATE_TEST_SUITE_P(
+    LeetCode, BinaryGapTest,
+    ::testing::ValuesIn(BinaryGapSolution().getStrategyNames()));
+
+}  // namespace problem_868
+}  // namespace leetcode