Question

Hi I have a List<decimal> containing values between ]0;1].
I want to check if a total (or subtotal) of these values can equal 1 (or almost).

I can also use Linq functions to filter or manipulate the list.

Desired results:

• A list containing {0.7, 0.7, 0.7} should return false;
• A list containing {0.7, 0.3, 0.7} should return true;
• A list containing {0.777777, 0.2, 0.1} should return false;
• A list containing {0.33333, 0.33333, 0.33333} should return true;
• A list containing {0.4, 0.5, 0.6, 0.3} should return true.

Obviously, I’ll want something with the lowest performance cost possible.

Answer 1

UPDATED — now doesn’t repetively sum
try this

bool isClose(IEnumerable<decimal> list, decimal epislon) {
  return isClose(Enumerable.Empty<decimal>(),list,0,list.Sum(),epislon);
}
// Define other methods and classes here
bool isClose(IEnumerable<decimal> left,IEnumerable<decimal> right, decimal leftSum,decimal rightSum, decimal epsilon) {
  if (leftSum>=1-epsilon && leftSum<=1+epsilon) return true;
  if (leftSum>1+epsilon) return false;
  if (leftSum+right.Sum()< 1-epsilon) return false;
  if (!right.Any()) return false;

  for (var i=0;i<right.Count();i++) {
    var skip=right.Skip(i);
    var newItem=skip.First();
    if (isClose(left.Concat(skip.Take(1)),skip.Skip(1),leftSum+newItem,rightSum-newItem,epsilon)) return true;
  }
  return false;
}



isClose(new[] {0.7m,0.7m,0.7m},0.001m); // returns false
isClose(new[] {0.7m,0.3m,0.7m},0.001m); //returns true
isClose(new[] {0.777777m,0.2m,0.1m},0.001m); //returns false
isClose(new[] {0.33333m,0.33333m,0.33333m},0.001m); //returns true

EDIT 5th Test

isClose(new[] {0.4m, 0.5m, 0.6m, 0.3m},0.001m); //returns true