//update This is the right sln which takes care of the negative and sequence building..
private SequenceSum FindMaxSumAndSequence2(int[] array)
{
//we can intialize to 0 but to handle negative number, i set it to min int
int maxsum = Int32.MinValue;
int sum = 0;
StringBuilder sequence = new StringBuilder();
string maxsequence = string.Empty;
for (int i = 0; i < array.Length; i++)
{
sum = sum + array[i];
sequence.Append(array[i]).Append(",");
if (maxsum < sum)
{
maxsum = sum;
maxsequence = sequence.ToString();
}
else if (sum < 0)
{
sum = 0; //reset sum to 0 when the sum value is negative
sequence.Clear();
}
}
SequenceSum result = new SequenceSum();
result.MaxSum = maxsum;
result.Sequence = maxsequence.ToString();
return(result);
}
private void button6_Click(object sender, EventArgs e)
{
int[] input = AlgorithmHelper.ConvertCommaSeparetedStringToInt(this.textBox11.Text);
SequenceSum result = FindMaxSumAndSequenceWithAllNegativeHandle(input);
this.textBox10.Text = result.MaxSum.ToString();
this.textBox12.Text = result.Sequence;
}
public void SequenceSum_Test_0()
{
int input = 0;
int[] expected = new int[] { 0 };
int[] actual = SequenceSum.SumOfN(input);
CollectionAssert.AreEqual(expected, actual);
}
public void SequenceSum_Test_Neg7()
{
int input = -7;
int[] expected = new int[] { 0, -1, -3, -6, -10, -15, -21, -28 };
int[] actual = SequenceSum.SumOfN(input);
CollectionAssert.AreEqual(expected, actual);
}
public void SequenceSum_Test_NegativeFour()
{
int input = -4;
int[] expected = new int[] { 0, -1, -3, -6, -10 };
int[] actual = SequenceSum.SumOfN(input);
CollectionAssert.AreEqual(expected, actual);
}
public void SequenceSum_Test_Ten()
{
int input = 10;
int[] expected = new int[] { 0, 1, 3, 6, 10, 15, 21, 28, 36, 45, 55 };
int[] actual = SequenceSum.SumOfN(input);
CollectionAssert.AreEqual(expected, actual);
}
//Logic: Maintain the maxsum value and sum value
//remember to reset sum to zero when the sum value is lesser than 0 bcoz when the negative value comes as sum..if we add to another negative worse sum or to positive still lesser than positive value
//Consider the scenario when the array contains all negative numbers..possible options 0, larger of negative or min_int..discuss with interviewer
private SequenceSum FindMaxSumAndSequenceWithAllNegativeHandle(int[] array)
{
//we can intialize to 0 but to handle negative number, i set it to min int
int maxsum = Int32.MinValue;
int sum = 0;
bool skippedsequence = false;
StringBuilder sb = new StringBuilder();
for (int i = 0; i < array.Length; i++)
{
sum = sum + array[i];
//only if the sum is greater than 0 append...ie build the sequence
if (sum > 0)
{
sb.Append(array[i]).Append(",");
}
if (maxsum < sum)
{
//Handle for negative number
//if the maxsum is already negative and the new sum is greater than maxsum..clear the sb
if (maxsum < 0 || (skippedsequence == true))
{
sb.Clear();
sb.Append(array[i]).Append(",");
skippedsequence = false;
}
maxsum = sum;
}
if (sum < 0)
{
sum = 0; //reset sum to 0 when the sum value is negative
//if sum is negative and maxsum is positive then we are skipped the number in sequence
//so we have to clear when we find the highest
if (maxsum > 0)
{
skippedsequence = true;
}
}
}
SequenceSum result = new SequenceSum();
result.MaxSum = maxsum;
result.Sequence = sb.ToString();
return(result);
}
