Counting Elements - Leetcode
Given an integer array arr , count element x such that x + 1 is also in arr . If there're duplicates in arr , count them seperately. 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's no 2, 4, 6, or 8 in arr. Example 3: Input: arr = [1,3,2,3,5,0] Output: 3 Explanation: 0, 1 and 2 are counted cause 1, 2 and 3 are in arr. Example 4: Input: arr = [1,1,2,2] Output: 2 Explanation: Two 1s are counted cause 2 is in arr. Constraints: 1 <= arr.length <= 1000 0 <= arr[i] <= 1000 Here the array to be converted as ArrayList or it can be done within the array itself . But if we done using only array then it consumes more time. Now consider for arraylist solution. 1)Retrieve each element from array using for each loop. 2)For each n element if there is n+1 then it is to be co