feat(work): add new LeetCode solution files for 1426, 1832, 344, and 15

work/3/Easy/Array/1426.counting-elements.py

@@ -0,0 +1,45 @@
+"""
+1426. Counting Elements
+Difficulty: Easy
+https://leetcode.com/problems/counting-elements/
+
+──────────────────────────────────────────────────
+
+Given an integer array arr, count how many elements x there are, such
+that x + 1 is also in arr. If there are duplicates in arr, count them
+separately.
+
+
+
+Example 1:
+
+Input: arr = [1,2,3]
+Output: 2
+Explanation: 1 and 2 are counted cause 2 and 3 are in arr.
+
+Example 2:
+
+Input: arr = [1,1,3,3,5,5,7,7]
+Output: 0
+Explanation: No numbers are counted, cause there is no 2, 4, 6, or 8
+in arr.
+
+
+
+Constraints:
+
+        • 1 <= arr.length <= 1000
+
+        • 0 <= arr[i] <= 1000
+"""
+
+
+class Solution:
+    def countElements(self, arr: List[int]) -> int:
+        arr_set = set(arr)
+        count = 0
+        for n in arr:
+            sum = n + 1
+            if sum in arr_set:
+                count += 1
+        return count