Ejemplo n.º 1
0
        //just playing for fun
        public static SubArrayResult maxsubArrayWithIndexMethod2(int[] array)
        {
            SubArrayResult result = new SubArrayResult();


            int           maxsum         = Int32.MinValue;
            int           runningsum     = 0;
            StringBuilder sbIndexrunning = new StringBuilder();
            StringBuilder maxIndexstring = new StringBuilder();

            for (int i = 0; i < array.Length; i++)
            {
                runningsum = runningsum + array[i];
                sbIndexrunning.Append(i).Append(',');

                if (runningsum > maxsum)
                {
                    maxsum         = runningsum;
                    maxIndexstring = sbIndexrunning;
                }

                if (runningsum < 0)
                {
                    runningsum = 0;
                    sbIndexrunning.Clear();
                }
            }

            if (maxIndexstring.Length > 0)
            {
                result.Sum = maxsum;
                string[] maxvalues = maxIndexstring.ToString().TrimEnd(',').Split(',');
                result.StartIndex = Convert.ToInt32(maxvalues[0]);
                result.EndIndex   = Convert.ToInt32(maxvalues[maxvalues.Length - 1]);
            }

            return(result);
        }
Ejemplo n.º 2
0
        //Kadane’s algorithm for 1D array
        public static SubArrayResult maxsubArrayWithIndex(int[] array)
        {
            int            maxsum           = Int32.MinValue;
            int            runningsum       = 0;
            List <int>     runningindexlist = new List <int>();
            List <int>     maxindexlist     = null;
            SubArrayResult result           = null;

            for (int i = 0; i < array.Length; i++)
            {
                runningsum = runningsum + array[i];
                runningindexlist.Add(i);

                if (runningsum > maxsum)
                {
                    maxsum       = runningsum;
                    maxindexlist = new List <int>(runningindexlist);
                }

                //reset sum to 0 when the sum value is negative
                if (runningsum < 0)
                {
                    runningsum = 0;
                    runningindexlist.Clear();
                }
            }

            if (maxindexlist.Count > 0)
            {
                result            = new SubArrayResult();
                result.Sum        = maxsum;
                result.StartIndex = maxindexlist[0];
                result.EndIndex   = maxindexlist[maxindexlist.Count - 1];
            }

            return(result);
        }
Ejemplo n.º 3
0
        public static MatrixSubArrayResult MaxSubMatrixWithIndex(int[,] matrix)
        {
            int rowcount = matrix.GetLength(0);
            int colcount = matrix.GetLength(1);

            int[] partialsum            = new int[colcount]; //size of colum
            int   maxsum                = Int32.MinValue;
            MatrixSubArrayResult result = new MatrixSubArrayResult();

            //test
            List <String> test = new List <string>();

            // 1 2 -1
            //-3 -1 -4
            // 1 -5 2
            // get all possible rows..
            //Now in this 3 x 3 matrix, the row can be grouped as [1],[1,2],[1,2,3],[2],[2,3],[3].

            for (int rowstart = 0; rowstart < rowcount; rowstart++)
            {
                ClearArray(partialsum);

                for (int rowend = rowstart; rowend < rowcount; rowend++)
                {
                    //here we will get all possible row grouping
                    //For the given row range ( 1 to 1 or 1 -3) we sum the col value
                    //p[0] will be the sum of first col
                    //p[1] will be the sume of secon col
                    //p[columcount -1]
                    //Important note: here we don't clear the array in this iteration
                    //becoze row of 1 result will be added to row of 2 and then three..
                    //we clear it only after the  master loop value changes
                    for (int i = 0; i < colcount; i++)
                    {
                        //This is an important piece..what we do is
                        //for [1 t0 1] row p[0] = 1 p[1] = 2 p[2] = -1
                        partialsum[i] = partialsum[i] + matrix[rowend, i];
                    }

                    //StringBuilder sb = new StringBuilder();
                    ////testing
                    //for (int j = 0; j < partialsum.Length; j++)
                    //{
                    //    sb.Append(partialsum[j]).Append(',');
                    //}
                    //test.Add(sb.ToString());
                    //here we can play with co-ordinates



                    SubArrayResult infores = maxsubArrayWithIndex(partialsum);
                    if (infores != null && infores.Sum > maxsum)
                    {
                        //maxsum = sum;
                        maxsum = infores.Sum;

                        result.Sum      = infores.Sum;
                        result.RowStart = rowstart;
                        result.RowEnd   = rowend;
                        result.ColStart = infores.StartIndex;
                        result.ColEnd   = infores.EndIndex;
                    }
                }
            }

            return(result);
        }