add: 230513-CN

cpp/2305/LC230513CN.cpp

@@ -0,0 +1,24 @@
+#include <algorithm>
+#include <vector>
+#include <unordered_set>
+
+/**
+ * 2441. Largest Positive Integer That Exists With Its Negative
+ *
+ * Given an integer array nums that does not contain any zeros, find the largest positive integer k such that -k also exists in the array.
+ * Return the positive integer k. If there is no such integer, return -1.
+ */
+
+class LC230513 {
+public:
+	static int findMaxK(const std::vector<int>&) noexcept;
+};
+
+int LC230513::findMaxK(const std::vector<int>& n) noexcept {
+	std::unordered_set<int> s(n.begin(), n.end());
+	int ret = -1;
+	for (int i: s)
+		if (s.count(-i))
+			ret = std::max(ret, std::abs(i));
+	return ret;
+}