add: 230510-CN

cpp/2305/LC230510CN.cpp

@@ -0,0 +1,30 @@
+#include <unordered_set>
+
+/**
+ * 1015. Smallest Integer Divisible by K
+ *
+ * Given a positive integer k, you need to find the length of the smallest positive integer n such that n is divisible by k, and n only contains the digit 1.
+ * Return the length of n. If there is no such n, return -1.
+ * Note: n may not fit in a 64-bit signed integer.
+ */
+
+class LC230510CN {
+public:
+	static int smallestRepunitDivByK(int k) noexcept;
+};
+
+int LC230510CN::smallestRepunitDivByK(int k) noexcept {
+	using ULL = unsigned long long;
+	int sum = 0;
+	std::unordered_set<ULL> vis;
+	ULL key;
+	for (int j = 1, c = 1;; (j = (j * 10) % k), ++c) {
+		sum = (sum + j) % k;
+		if (sum == 0)
+			return c;
+		key = (ULL(sum) << 32) + j;
+		if (vis.contains(key))
+			return -1;
+		vis.insert(key);
+	}
+}

cpp/2305/defs.h

@@ -108,4 +108,9 @@ public:
 	static std::vector<int> spiralOrder(const std::vector<std::vector<int>>&) noexcept;
 };
 
+class LC230510CN {
+public:
+	static constexpr inline int smallestRepunitDivByK(int k) noexcept;
+};
+
 #endif //LEETCODE_CPP_DEFS_H

cpp/2305/main.cpp

@@ -1,5 +1,7 @@
+#include <cstdio>
 #include <iostream>
 #include <ostream>
+#include <unordered_set>
 #include <vector>
 
 #include "defs.h"
@@ -12,11 +14,27 @@ std::ostream& operator<<(std::ostream& os, const std::vector<T>& x) noexcept {
 }
 
 int main() {
-	std::cout << LC230509::spiralOrder({
-		{2,3,4},
-		{5,6,7},
-		{8,9,10},
-		{11,12,13}
-	});
+	using ULL = unsigned long long;
+	int ok = 0, not_ok = 0;
+	for (int i : {99, 101, 9999}) {
+		int sum = 0;
+		std::unordered_set<ULL> vis;
+		for (int j = 1, c = 1;; (j = (j * 10) % i), ++c) {
+			sum = (sum + j) % i;
+			if (sum == 0) {
+				std::printf("%6d -> %d\n", i, c);
+				++ok;
+				break;
+			}
+			auto key = (ULL(sum) << 32) + j;
+			if (vis.contains(key)) {
+				std::printf("%6d -> CANNOT\n", i);
+				++not_ok;
+				break;
+			}
+			vis.insert(key);
+		}
+	}
+	std::printf("[OK] %d | [FAIL] %d\n", ok, not_ok);
 	return 0;
 }