add: 220411-CN [cpp]

cpp/2204/220411-CN.cpp

@@ -0,0 +1,35 @@
+#include <cstdio>
+
+/**
+ * 357. Count Numbers with Unique Digits
+ * Given an integer n, return the count of all numbers with unique digits, x, where 0 <= x < 10^n.
+ */
+
+class Solution {
+public:
+	static int countNumbersWithUniqueDigits(int n) {
+		static const int ans[] = {1, 10, 91, 739, 5275, 32491, 168571, 712891, 2345851};
+		return ans[n];
+	}
+};
+
+bool isUnique(int x) {
+	int c[10]{};
+	for (; x; x /= 10)
+		if (c[x % 10]++)
+			return false;
+	return true;
+}
+
+int main() {
+	int ans = 0;
+	for (int i = 0, j = 1; i < 9; ++i, j *= 10) {
+		for (int k = j / 10; k < j; ++k) {
+			if (isUnique(k)) {
+				++ans;
+			}
+		}
+		std::printf("%d(%d) -> %d\n", i, j, ans);
+	}
+	return 0;
+}

cpp/2204/CMakeLists.txt

@@ -3,4 +3,4 @@ PROJECT(2204)
 
 SET(CMAKE_CXX_STANDARD 23)
 
-ADD_EXECUTABLE(2204 220410-CN.cpp)
+ADD_EXECUTABLE(2204 220411-CN.cpp)