add: 220409 [cpp]

cpp/2204/220409.cpp

@@ -0,0 +1,86 @@
+#include <unordered_set>
+#include <vector>
+#include <unordered_map>
+#include <queue>
+
+class Solution {
+public:
+	static std::vector<int> topKFrequent(const std::vector<int>& nums, int k) {
+		auto* cnt = new std::unordered_set<int>[100000 + 1];
+		std::unordered_map<int, int> m;
+		int max_cnt = 1;
+		for (int x : nums) {
+			if (!m.count(x)) {
+				m[x] = 1;
+				cnt[1].insert(x);
+			} else {
+				cnt[m[x]].erase(x);
+				cnt[++m[x]].insert(x);
+				max_cnt = std::max(max_cnt, m[x]);
+			}
+		}
+		std::vector<int> ret;
+		for (int i = max_cnt; i > 0 && k > 0; --i) {
+			if (cnt[i].size() <= k) {
+				k -= cnt[i].size();
+				ret.insert(ret.end(), cnt[i].cbegin(), cnt[i].cend());
+			} else {
+				ret.insert(ret.end(), cnt[i].begin(), std::next(cnt[i].begin(), k));
+			}
+		}
+		delete[] cnt;
+		return ret;
+	}
+};
+
+class Solution2 {
+public:
+	static std::vector<int> topKFrequent(const std::vector<int>& nums, int k) {
+		std::unordered_map<int, int> m;
+		for (int x : nums)
+			++m[x];
+		std::priority_queue<std::pair<int, int>, std::vector<std::pair<int, int>>, std::greater<>> q;
+		for (const auto& [idx, cnt] : m) {
+			q.push({cnt, idx});
+			if (q.size() > k)
+				q.pop();
+		}
+		while (q.size() > k)
+			q.pop();
+		std::vector<int> ret;
+		ret.reserve(k);
+		while (!q.empty()) {
+			ret.push_back(q.top().second);
+			q.pop();
+		}
+		return ret;
+	}
+};
+
+struct PairSecondCmp {
+	bool operator()(const std::pair<int, int> x, const std::pair<int, int> y) {
+		return x.second < y.second;
+	}
+};
+
+class Solution3 {
+public:
+	static std::vector<int> topKFrequent(const std::vector<int>& nums, int k) {
+		std::unordered_map<int, int> m;
+		for (int x : nums)
+			++m[x];
+		std::priority_queue<std::pair<int, int>, std::vector<std::pair<int, int>>, PairSecondCmp> q(m.begin(), m.end());
+		std::vector<int> ret;
+		ret.reserve(k);
+		for (int i = 0; i < k; ++i) {
+			ret.push_back(q.top().second);
+			q.pop();
+		}
+		return ret;
+	}
+};
+
+int main() {
+	auto ret = Solution3::topKFrequent({5,2,5,3,5,3,1,1,3}, 2);
+	return 0;
+}

cpp/2204/CMakeLists.txt

@@ -3,4 +3,4 @@ PROJECT(2204)
 
 SET(CMAKE_CXX_STANDARD 23)
 
-ADD_EXECUTABLE(2204 220409-CN.cpp)
+ADD_EXECUTABLE(2204 220409.cpp)