unique_values.dart

void main() {
  final result = sumZero([-6, -5, 0, 1, 2, 3, 4]);
  print(result);
  print(uniqueCount([-2,-1,-1, 0,1]));
}

//assume it receives a sorted array
// return a pair of values whose sum is 0 otherwise undefined
//using multiple pointers pattern

List<int>? sumZero(List<int> array) {
  int left = 0;
  int right = array.length - 1;
  while (left < right) {
    final sum = array[left] + array[right];
    if (sum == 0) {
      return [array[left], array[right]];
    } else if (sum > 0) {
      right--;
    } else {
      left++;
    }
  }
  return null;
}

int uniqueCount(List<int> array){
  var count = 0;
  if(array.isEmpty) return count;
  count += 1;
  var i = 0;
  var j = i + 1;
  
  while(i < array.length && j < array.length) {
//     print(j);
   if(array[i] != array[j]){
     count += 1;
   }
    i++;
    j++;
  }
  return count;
}

// O(n) time complexity
// O(1) space complexity