Day 7 of 30-Day LeetCode Challenge

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.

class Solution {
int countElements(vector<int>& arr) { //O(nlogn)
sort(arr.begin(), arr.end());
int result = 0;
for(int i=0;i<arr.size();){
int j = i+1;
if(j<arr.size()&&arr[i]+1==arr[j]) {
//cout<<i<<”, “<<j<<endl;
result += j-i;

i = j;
return result;



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