Tuesday, December 20, 2011

Getting Combinations in c++

we had programming exercise and I needed to put a function to return K combinations from N numbers starting from 1
So for example of N = 10, K = 3
I would have combinations starting from
1,2,3 - 1,2,4 – 1,2,5 – 1,2,6 – … and so on  till 8,9,10
I found some function to do this in c# here
I took the same algorithm and wrote it in c++ using vectors
below is the 2 functions I used, getCombinations will return the combinations vector
vector<vector<int> > getCombinations(int n, int k)
    // define variales
    vector<vector<int> > combincations;
    vector<int> row;
    for(int i=0;i<k; i++)
    row[0] = 1;
    // call the iterate function
    return combincations;
void iterate(int i, vector<vector<int> > &c, vector<int> &row, int n, int k )
    /// i represents the current index in the row vector that is used to fill the c matrix with combinations
    // set the i term to previous term +1
        row[i] = row[i-1] +1;
    //for loop to increment the current cell in the row till it reachs n-k+i+1
    // we are using n-k+i because we want to reach different values depending on the index
    // for example in N = 10, k = 3, first cell will increase till 8, second till 9, third till 10
    // so the last combination is 8,9,10
    for(;row[i] <= (n - k + i + 1);row[i]++)
        // if this is not the last index, call iterate with next index
        // else fill in the combinations matrix
        if (i < k - 1)
            iterate(i + 1, c, row, n, k);
            vector<int> combination = row; //copying the row content
            c.push_back(combination); // adding the row to combinations vector

Wednesday, December 7, 2011

testlink: setting up MySQL Daily backup job

We wanted to keep our data safe, so we started taking backups using phpmyadmin, and because of forgetting sometimes, we thought of automating the backup

After doing some search, using the information from this page http://dev.mysql.com/doc/refman/5.1/en/mysqldump.html

I created a batch file, called DailyBackup.bat for example

and wrote the below in the batch file

for /f "tokens=1-4 delims=/ " %%a in ('date/t') do (
set dw=%%a
set mm=%%b
set dd=%%c
set yy=%%d

SET bkupdir="path to backup folder"
SET mysqldir="C:\Program Files (x86)\EasyPHP5.3.0\mysql"
SET dbname=testlink

SET dbuser=username

SET password=password

set zip="C:\Program Files (x86)\GnuWin32\bin\gzip.exe"
@ECHO Beginning backup of %dbname%...

%mysqldir%\bin\mysqldump -B %dbname% -u %dbuser% –p%password% | %zip% > %bkupdir%\dbBkup_%dbname%_%dd%%mm%%dw%.sql.gzip

The above batch file needs gzip to be installed

Then I created a scheduled task that runs daily and executes the above batch file