leetcode

commit 5a210dfaefaa53cfa6f3152c23d992c93e83c4cf
parent e005e72b441ae5d8f214adaace18a2312f8be2cf
Author: Jack Sangdahl <jack@pngu.org>
Date:   Sat, 26 Apr 2025 19:27:09 -0600

3392. count subarrays of length three with a condition

Diffstat:
A
count_subarr_len_three_cond.c
 | 
22
++++++++++++++++++++++
A
count_subarr_len_three_cond.py
 | 
22
++++++++++++++++++++++

2 files changed, 44 insertions(+), 0 deletions(-)
diff --git a/count_subarr_len_three_cond.c b/count_subarr_len_three_cond.c
@@ -0,0 +1,22 @@
+// 3392. Count Subarrays of Length Three With a Condition
+#include "leetcode.h"
+
+/*
+ * given an integer array 'nums', return the number of subarrays of length 3
+ * such that the sum of the first and third number equals exactly half of the
+ * second number.
+ */
+
+int countSubarrays(int *nums, int numsSize) {
+  int cnt = 0;
+  for (int i = 1; i < numsSize - 1; ++i)
+    if (2 * (nums[i - 1] + nums[i + 1]) == nums[i])
+      cnt++;
+  return cnt;
+}
+
+int main() {
+  int n1[] = {1, 2, 1, 4, 1}, n2[] = {1, 1, 1};
+  printf("%d\n", countSubarrays(n1, ARRAY_SIZE(n1))); // expect: 1
+  printf("%d\n", countSubarrays(n2, ARRAY_SIZE(n2))); // expect: 0
+}
diff --git a/count_subarr_len_three_cond.py b/count_subarr_len_three_cond.py
@@ -0,0 +1,22 @@
+# 3392. Count Subarrays of Length Three With a Condition
+
+"""
+given an integer array 'nums', return the number of subarrays of length 3
+such that the sum of the first and third number equals exactly half of the
+second number.
+"""
+
+
+class Solution(object):
+    def countSubarrays(self, nums):
+        """
+        :type nums: List[int]
+        :rtype: int
+        """
+        return sum(l + r << 1 == m for l, m, r in zip(nums, nums[1:], nums[2:]))
+
+
+if __name__ == "__main__":
+    obj = Solution()
+    print(obj.countSubarrays(nums=[1, 2, 1, 4, 1]))
+    print(obj.countSubarrays(nums=[1, 1, 1]))