Develop Reference

Can't perambulate indexes in matrix the right way

Hello. I have this task to sum the numbers as shown. Tried everything I can, but still not the right answer. Can I have some guidance?
static void Main(string[] args)
{
string input = Console.ReadLine();
int n = (int)char.GetNumericValue(input[0]);
int m = (int)char.GetNumericValue(input[2]);
int[,] matrix = new int[n, m];
int sum = 0;
//fill matrix
for (int i = 0; i < n; i++)
{
for (int j = 0; j < m; j++)
{
matrix[i, j] = (j * 3 + 1) + i * 3;
}
}
for (int i = 0; i < matrix.GetLength(0) - 1; i+=1)
{
for (int j = 0; j < matrix.GetLength(1) - i; j+=1)
{
if (i % 2 == 0)
{
sum += matrix[i, j + i] + matrix[i + 1, j + 1];
}
}
}
Console.WriteLine(sum);
}

I think you would've a easier time hard coding the input (and naming them as "columns" and "rows" instead, much more readable).
What is the expected output? Not sure I'm following this sum. I'm guessing, 297? If so:
for (int i = 0; i < matrix.GetLength(0); i++)
{
for (int j = 0; j < matrix.GetLength(1); j++)
{
Console.Write(matrix[i, j] + " ");
if(j == 5) Console.WriteLine();
if (matrix[i, j] % 2 != 0)
{
if (i == 0 || i == matrix.GetLength(0) - 1
|| j == 0 || j == matrix.GetLength(0))
{
sum += (matrix[i, j]);
}
else
{
sum += (matrix[i, j] * 2);
}
}
}
}

How to save a pyramid into array of chars?

I need help with checking IF the position in array must save ' ' or '*' for later in program to print out a pyramid.
static void Main(string[] args)
{
Console.WriteLine("Enter size: ");
int s = int.Parse(Console.ReadLine());
char[,] pyramid = new char[s, s * 2 - 1];
FillArray(pyramid);
Out(pyramid);
Console.ReadLine();
}
static void FillArray(char[,] t)
{
for (int i = 0; i < t.GetLength(0); i++)
{
for (int j = 0; j < t.GetLength(1); j++)
{
if (j == t.GetLength(1) / 2 || j == t.GetLength(1) / 2 + i || j == t.GetLength(1) / 2 - i)
{
t[i, j] = '*';
}
else t[i, j] = ' ';
}
}
}
static void Out(char[,] t)
{
for (int i = 0; i < t.GetLength(0); i++)
{
for (int j = 0; j < t.GetLength(1); j++)
{
Console.Write(t[i, j]);
}
Console.WriteLine();
}
}
At the moment I get out something like this:

The code should be like this
int i, j, n;
Console.WriteLine("Enter size: ");
n = int.Parse(Console.ReadLine());
for (i = 0; i < n; i++)
{
for (j = 1; j <= n - i; j++)
Console.Write(" ");
for (j = 1; j <= 2 * i - 1; j++)
Console.Write("*");
Console.Write("\n");
}

Sequence of marching chars in 2 strings

I have to write searching algorithm, For example I have to compare str="giorgi" to str2="grigol". I'm trying to find longest matching sequence of chars, so that the order of chars is the same and string which I should get is "grg"... with this c# code I'm getting "grig".
int k=0;
string s="";
string str = "giorgi";
string str2 = "grigol";
for(int i=0;i<str.Length;i++)
{
for (int j = k; j < str2.Length; j++)
{
if (str[i] == str2[j])
{
s += str2[k];
k++;
goto endofloop;
}
}
endofloop:;
}
Console.WriteLine(s);

The solution:
using System;
class GFG
{
/* Returns length of LCS for X[0..m-1], Y[0..n-1] */
static int lcs( char[] X, char[] Y, int m, int n )
{
int [,]L = new int[m+1,n+1];
/* Following steps build L[m+1][n+1]
in bottom up fashion. Note
that L[i][j] contains length of
LCS of X[0..i-1] and Y[0..j-1] */
for (int i = 0; i <= m; i++)
{
for (int j = 0; j <= n; j++)
{
if (i == 0 || j == 0)
L[i, j] = 0;
else if (X[i - 1] == Y[j - 1])
L[i, j] = L[i - 1, j - 1] + 1;
else
L[i, j] = GFG.max(L[i - 1, j], L[i, j - 1]);
}
}
return L[m, n];
}
static int max(int a, int b)
{
return (a > b)? a : b;
}
}
And now the program to test it:
public static void Main()
{
String s1 = "giorgi";
String s2 = "grigol";
char[] X=s1.ToCharArray();
char[] Y=s2.ToCharArray();
int m = X.Length;
int n = Y.Length;
Console.Write("Length of LCS is" + " " +lcs( X, Y, m, n ) );
}
}

C# LevenshteinDistance algorithm for spellchecker

Hi i'm using the levenshtein algorithm to calculate the difference between two strings, using the below code. It currently provides the total number of changes which need to be made to get from 'answer' to 'target', but i'd like to split these up into the types of errors being made. So classifying an error as a deletion, substitution or insertion.
I've tried adding a simple count but i'm new at this and don't really understand how the code works so not sure how to go about it.
static class LevenshteinDistance
{
/// <summary>
/// Compute the distance between two strings.
/// </summary>
public static int Compute(string s, string t)
{
int n = s.Length;
int m = t.Length;
int[,] d = new int[n + 1, m + 1];
// Step 1
if (n == 0)
{
return m;
}
if (m == 0)
{
return n;
}
// Step 2
for (int i = 0; i <= n; d[i, 0] = i++)
{
}
for (int j = 0; j <= m; d[0, j] = j++)
{
}
// Step 3
for (int i = 1; i <= n; i++)
{
//Step 4
for (int j = 1; j <= m; j++)
{
// Step 5
int cost = (t[j - 1] == s[i - 1]) ? 0 : 1;
// Step 6
d[i, j] = Math.Min(
Math.Min(d[i - 1, j] + 1, d[i, j - 1] + 1),
d[i - 1, j - 1] + cost);
}
}
// Step 7
return d[n, m];
}
}
Thanks in advance.

create asterisk tree with C#

Hello everyone
I try to solve asterisk tree problem
and found my code is not work correctly and can be improved.
This is output that expected
input : 5
*
* * *
* * * * *
* * *
*
input : 4
* * * *
* *
* * * *
and this is my code
static void Main(string[] args)
{
Console.Write("input:");
char input = Console.ReadKey().KeyChar;
if (char.IsDigit(input))
{
int couter = (int)char.GetNumericValue(input);
Console.WriteLine();
if (couter % 2 != 0)
{
for (int i = 1; i <= couter; i++)
{
for (int j = 3; j > i; j--)
{
Console.Write(" ");
}
for (int k = 1; k <= i; k++)
{
Console.Write(" *");
}
Console.WriteLine();
}
for (int i = couter - 1; i >= 3; i--)
{
for (int j = 1; j <= i; j++)
{
if (j <= couter - i)
{
Console.Write(" ");
}
else
{
Console.Write("* ");
}
}
Console.WriteLine();
}
}
else
{
for (int i = couter; i > 3; i--)
{
for (int j = 1; j <= i; j++)
{
if (couter - i >= j)
{
Console.Write(" ");
}
else
{
Console.Write("* ");
}
}
Console.WriteLine();
}
for (int i = couter - 1; i <= couter; i++)
{
for (int j = 0; j < i; j++)
{
Console.Write("* ");
}
Console.WriteLine();
}
}
}
}
Please could you help me to solve this problem.
Lately, I think I'm poor at algorithms and a little complex problem. Is anybody know useful link or how I can improve this skill, please let me know.
Thanks,

Check this page for input 5 (diamond) : http://www.dreamincode.net/forums/topic/126715-diamond-asterisk/
I've translated it to C# - now it displays diamonds with size that you set in variable 'rows':
int rows = 5;
StringBuilder sb = new StringBuilder();
// top part
for (int i = 1; i <= rows; i++)
{
for (int j = 1; j <= rows - i; j++)
sb.Append(' ');
for (int k = 1; k <= 2 * i - 1; k++)
sb.Append('*');
sb.AppendLine();
}
//bottom part
for (int n = rows - 1; n > 0; n--)
{
for (int l = 1; l <= rows - n; l++)
sb.Append(' ');
for (int m = 1; m <= 2 * n - 1; m++)
sb.Append('*');
sb.AppendLine();
}
Console.Write(sb.ToString());

I was initially reluctant to post it because it definitely smells like homework...
Anyway, here's a piece of working code:
static void Main(string[] args)
{
Console.Write("input:");
char input = Console.ReadKey().KeyChar;
if (char.IsDigit(input))
{
int couter = (int)char.GetNumericValue(input);
Console.WriteLine();
if (couter % 2 != 0)
PrintDiamond(couter);
else
PrintHourGlass(couter);
}
Console.ReadLine();
}
private static void PrintDiamond(int couter)
{
bool moreAsterisks = true;
for (int row = 0; row < couter; row++)
{
int nAsterisks = moreAsterisks ? (2 * row) + 1 : 2 * (couter - row - 1) + 1;
int nSpaces = (couter - nAsterisks) / 2;
if (row == (couter - 1) / 2)
moreAsterisks = false;
for (int i = 0; i < nSpaces; i++)
Console.Write(" ");
for (int i = 0; i < nAsterisks; i++)
Console.Write("*");
for (int i = 0; i < nSpaces; i++)
Console.Write(" ");
Console.WriteLine();
}
}
private static void PrintHourGlass(int couter)
{
bool moreAsterisks = false;
for (int row = 0; row < couter - 1; row++)
{
int nAsterisks = moreAsterisks ? couter - 2 * (couter - row - 2) : couter - (2 * row);
int nSpaces = (couter - nAsterisks) / 2;
if (row == (couter - 2) / 2)
moreAsterisks = true;
for (int i = 0; i < nSpaces; i++)
Console.Write(" ");
for (int i = 0; i < nAsterisks; i++)
Console.Write("*");
for (int i = 0; i < nSpaces; i++)
Console.Write(" ");
Console.WriteLine();
}
}
P.S.:
it works with any number, not just 4-5...

Here's a minified LINQ solution for your problem:
class Program
{
static void Main(string[] args)
{
Console.Write("input: ");
string line = Console.ReadLine();
int n;
if (!int.TryParse(line, out n))
{
Console.WriteLine("Enter a valid integer number.");
return;
}
for (int i = 0; i < n; i++)
{
int l = Math.Abs(n - i * 2 - 1) + 1;
if (n % 2 != 0) l = n - l + 1;
Console.Write(Enumerable.Repeat(" ", n - l).DefaultIfEmpty("").Aggregate((a, b) => a + b));
Console.WriteLine(Enumerable.Repeat("* ", l).DefaultIfEmpty("").Aggregate((a, b) => a + b));
}
}
}
It's pretty simple; inside the loop, first line calculates length of the i-th diamond row if input is even, second one corrects the calculation for odd input. The remaining two lines print i-th row using some LINQ tricks. If you don't like showing off with LINQ, you can replace thoose lines with regular for loops (which is probably going to be faster). Then the code would look like:
class Program
{
static void Main(string[] args)
{
Console.Write("input: ");
string line = Console.ReadLine();
int n;
if (!int.TryParse(line, out n))
{
Console.WriteLine("Enter a valid integer number.");
return;
}
for (int i = 0; i < n; i++)
{
int l = Math.Abs(n - i * 2 - 1) + 1;
if (n % 2 != 0) l = n - l + 1;
//Console.Write(Enumerable.Repeat(" ", n - l).DefaultIfEmpty("").Aggregate((a, b) => a + b));
//Console.WriteLine(Enumerable.Repeat("* ", l).DefaultIfEmpty("").Aggregate((a, b) => a + b));
for (int c = 0; c < n - l; c++) Console.Write(" ");
for (int c = 0; c < l; c++) Console.Write("* ");
Console.WriteLine();
}
}
}