diff --git a/cpp/2303/230316-CN.cpp b/cpp/2303/230316-CN.cpp new file mode 100644 index 0000000..22db3f2 --- /dev/null +++ b/cpp/2303/230316-CN.cpp @@ -0,0 +1,44 @@ +#include +#include +#include + +/** + * 2488. Count Subarrays With Median K + * + * You are given an array nums of size n consisting of distinct integers from 1 to n and a positive integer k. + * + * Return the number of non-empty subarrays in nums that have a median equal to k. + * + * Note: + * + * The median of an array is the middle element after sorting the array in ascending order. If the array is of even length, the median is the left middle element. + * For example, the median of [2,3,1,4] is 2, and the median of [8,4,3,5,1] is 4. + * A subarray is a contiguous part of an array. + */ + +class Solution { +private: + static inline constexpr int sgn(int x) { return (x > 0) - (x < 0); } + +public: + static int countSubarrays(const std::vector& nums, int k) { + const int n = nums.size(), pos = std::find(nums.begin(), nums.end(), k) - nums.begin(); + std::vector prefix(n); + prefix[0] = sgn(nums[0] - k); + for (int i = 1; i < n; ++i) + prefix[i] = prefix[i - 1] + sgn(nums[i] - k); + std::unordered_map m; + for (int i = 0; i < pos; ++i) + ++m[prefix[i]]; + ++m[0]; + int ans = 0; + for (int i = pos; i < n; ++i) + ans += m[prefix[i]] + m[prefix[i] - 1]; + return ans; + } +}; + +int main() { + std::cout << Solution::countSubarrays({3,2,1,4,5}, 4); + return 0; +} diff --git a/cpp/2303/CMakeLists.txt b/cpp/2303/CMakeLists.txt index 250d13c..f40afe4 100644 --- a/cpp/2303/CMakeLists.txt +++ b/cpp/2303/CMakeLists.txt @@ -3,4 +3,4 @@ PROJECT(2303) SET(CMAKE_CXX_STANDARD 23) -ADD_EXECUTABLE(2303 230315-CN.cpp) +ADD_EXECUTABLE(2303 230316-CN.cpp)