Python3 : arr = [2, 2, 1, 3, 3, 4, 5, 2, 2] bank = [] bank2 = [] sum = 0 for i in range(len(arr)): if arr[i] not in bank: sum += arr[i] bank.append(arr[i]) elif arr[i] in bank and arr[i] not in bank2: sum -= arr[i] bank2.append(arr[i]) print(sum)

If arr[i] ==arr[i+1], add 2 to the value of i or index . *Note:- We have to actually add 2 to the index or i to hop the two duplicate numbers. Since in the for loop we already have i++, so we are adding 1 to i , when arr[i]==arr[i+1] const arr = [1, 2, 3, 3, 4, 5, 7, 4, 4]; let sum = 0; for (let i = 0; i < arr.length; i++) { if (arr[i] === arr[i + 1]) { console.log(`duplicate Element: ${arr[i]}`); i = i + 1; //adding 1 to i Since in the for loop we already have i++ } else { sum += arr[i]; } } console.log(`Sum is:${sum}`);

javascript function AddNonRepeating(arr) { if (arr.length == 0) { return 0; } else { arr.sort(); let current = arr[0]; let add = 0; let flag = 0; for (let i = 1; i < arr.length; i++) { if (current != arr[i] && flag == 0) { add += current; current = arr[i]; } else if (current != arr[i]) { flag = 0; current = arr[i]; } else { flag = 1; current = arr[i]; } } if (arr[arr.length - 2] != arr[arr.length - 1]) { add += arr[arr.length - 1]; } return add; } } console.log(AddNonRepeating([1, 2, 3, 4, 5, 2, 3]));