S18 - hasDuplicates Time Complexity

hasDupTC

var hasDuplicates = function(array){
  for(var i = 0; i < array.length; i++){
    var item = array[i];
    if(array.slice(i+1).indexOf(item) !== -1){
      return true;
    }
  }
  return false;
};
/*
Line 2: Loop time complexity linear.
Line 4 worst case:
n-i operations for the slice, and n-i operations for the indexOf 
So 2n-2i, where i is a constant less than N.
n*(Cn - Y) reduces to O(n^2).
Credit to John Tan for explaining this to me.
 */