leetcode

commit 2e0c50092c4094ed3262e8631dbb57e87f4bf5a5
parent 441a61937d0fe800e01d78999850affb39e8e88b
Author: Jack Sangdahl <jack@pngu.org>
Date:   Mon, 24 Nov 2025 18:30:31 -0700

1015. smallest integer divisible by k

Diffstat:
A
smallest_int_div_k.c
 | 
22
++++++++++++++++++++++
A
smallest_int_div_k.py
 | 
30
++++++++++++++++++++++++++++++

2 files changed, 52 insertions(+), 0 deletions(-)
diff --git a/smallest_int_div_k.c b/smallest_int_div_k.c
@@ -0,0 +1,22 @@
+// 1015. Smallest Integer Divisible by K
+#include "leetcode.h"
+
+/*
+ * given a positive integer 'k', you need to find the length of the smallest
+ * positive intger '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.
+ */
+
+int smallestRepunitDivByK(int k) {
+  for (int i = 0, j = 1; j <= k; ++j)
+    if (!(i = (i * 10 + 1) % k))
+      return j;
+  return -1;
+}
+
+int main() {
+  printf("%d\n", smallestRepunitDivByK(1)); // expect: 1
+  printf("%d\n", smallestRepunitDivByK(2)); // expect: -1
+  printf("%d\n", smallestRepunitDivByK(3)); // expect: 3
+}
diff --git a/smallest_int_div_k.py b/smallest_int_div_k.py
@@ -0,0 +1,30 @@
+# 1015. Smallest Integer Divisible by K
+
+"""
+given a positive integer 'k', you need to find the length of the smallest
+positive intger '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 Solution(object):
+    def smallestRepunitDivByK(self, k):
+        """
+        :type k: int
+        :rtype: int
+        """
+        if k % 2 == 0 or k % 5 == 0:
+            return -1
+        i = 0
+        for j in range(1, k + 1):
+            i = (i * 10 + 1) % k
+            if not i:
+                return j
+
+
+if __name__ == "__main__":
+    obj = Solution()
+    print(obj.smallestRepunitDivByK(k=1))
+    print(obj.smallestRepunitDivByK(k=2))
+    print(obj.smallestRepunitDivByK(k=3))