add: 220507 [cpp]

cpp/2205/220507.cpp

@@ -0,0 +1,95 @@
+#include <vector>
+#include <map>
+#include <stack>
+#include <cstdio>
+#include <chrono>
+
+/**
+ * 456. 132 Pattern
+ * Given an array of n integers nums, a 132 pattern is a subsequence of three integers nums[i], nums[j] and nums[k] such that i < j < k and nums[i] < nums[k] < nums[j].
+ * Return true if there is a 132 pattern in nums, otherwise, return false.
+ */
+
+class Solution {
+public:
+	static bool find132pattern(const std::vector<int>& nums) {
+		const int n = nums.size();
+		int ptr = 0;
+		int* s = new int[n];
+		int e3 = -0x7FFFFFFF - 1, t, st;
+		// for (auto it = nums.crbegin(); it != nums.crend(); ++it) {
+		for (int i = n - 1; i >= 0; --i) {
+			t = nums[i];
+			if (t < e3)
+				return true;
+			while (ptr && (st = s[ptr - 1]) < t) {
+				e3 = st;
+				--ptr;
+			}
+			s[ptr++] = t;
+		}
+		return false;
+	}
+};
+
+class SolutionOld {
+public:
+	static bool find132pattern(const std::vector<int>& nums) {
+		const int n = nums.size();
+		if (n < 3)
+			return false;
+		std::map<int, int> m;
+		for (int i = 1; i < n; ++i)
+			++m[nums[i]];
+		int min = nums[0], pivot = 1;
+		while (pivot < n - 1) {
+			auto it = std::lower_bound(m.cbegin(), m.cend(), std::pair<const int, int>(min, 0x7FFFFFFF));
+			if (it != m.end() && it->first < nums[pivot])
+				return true;
+
+			// Advance pivot
+			int prevPivot = pivot, prevMin = min;
+			while (pivot < n - 1 && ((nums[pivot] <= nums[prevPivot] && prevMin == min) || nums[pivot] <= nums[pivot + 1])) {
+				if (--m[nums[pivot]] <= 0) {
+					m.erase(nums[pivot]);
+				}
+				min = std::min(min, nums[pivot]);
+				++pivot;
+			}
+			if (pivot == prevPivot) {
+				min = std::min(min, nums[pivot]);
+				++pivot;
+			}
+		}
+		return false;
+	}
+};
+
+class Stopwatch {
+private:
+	std::chrono::high_resolution_clock::time_point start;
+public:
+	Stopwatch() {
+		this->start = std::chrono::high_resolution_clock::now();
+	}
+
+	~Stopwatch() {
+		std::printf("Time elapsed: %.6lf ms\n", std::chrono::duration_cast<std::chrono::nanoseconds>(std::chrono::high_resolution_clock::now() - start).count() / 1000000.0);
+	}
+};
+
+int main() {
+	const int N = 200000;
+	std::vector<int> args(N);
+	for (int i = 0; i < N; ++i)
+		args[i] = (i & 1) ? -i : i;
+
+	bool ans;
+	{
+		Stopwatch s;
+		ans = Solution::find132pattern(args);
+	}
+
+	std::printf(ans ? "true" : "false");
+	return 0;
+}

cpp/2205/CMakeLists.txt

@@ -3,4 +3,4 @@ PROJECT(2205)
 
 SET(CMAKE_CXX_STANDARD 23)
 
-ADD_EXECUTABLE(2205 220507-CN.cpp)
+ADD_EXECUTABLE(2205 220507.cpp)