add: 220214-CN

2202/220214-CN.cpp

@@ -0,0 +1,35 @@
+#include <vector>
+#include <cstdio>
+
+/**
+ * 540. Single Element in a Sorted Array
+ * You are given a sorted array consisting of only integers where every element appears exactly twice, except for one element which appears exactly once.
+ * Return the single element that appears only once.
+ * Your solution must run in O(log n) time and O(1) space.
+ */
+
+class Solution {
+public:
+	static int singleNonDuplicate(const std::vector<int>& nums) {
+		int L = 0, R = nums.size();
+		if (R == 1)
+			return nums[0];
+
+		// Interval [L, R)
+		while (R - L > 1) {
+			int M = (L + R) >> 1;
+			if (nums[M] == nums[M ^ 1]) {
+				L = 1 + (M | 1);
+			} else {
+				R = (M & (~1)) + 1;
+			}
+		}
+
+		return nums[L];
+	}
+};
+
+int main() {
+	std::printf("%d\n", Solution::singleNonDuplicate({1,1,2,3,3}));
+	return 0;
+}

2202/CMakeLists.txt

@@ -3,4 +3,4 @@ PROJECT(2202)
 
 SET(CMAKE_CXX_STANDARD 23)
 
-ADD_EXECUTABLE(2202 220213.cpp)
+ADD_EXECUTABLE(2202 220214-CN.cpp)