/**
* Recursive maximum contiguous subsequence sum algorithm.
* Finds maximum sum in subarray spanning a[left..right].
* Does not attempt to maintain actual best sequence.
*/
int maxSumRec( const vector<int> & a, int left, int right )
{
/* 1*/ if( left == right ) // Base case
/* 2*/ if( a[ left ] > 0 )
/* 3*/ return a[ left ];
else
/* 4*/ return 0;
/* 5*/ int center = ( left + right ) / 2;
/* 6*/ int maxLeftSum = maxSumRec( a, left, center );
/* 7*/ int maxRightSum = maxSumRec( a, center + 1, right );
/* 8*/ int maxLeftBorderSum = 0, leftBorderSum = 0;
/* 9*/ for( int i = center; i >= left; i-- )
{
/*10*/ leftBorderSum += a[ i ];
/*11*/ if( leftBorderSum > maxLeftBorderSum )
/*12*/ maxLeftBorderSum = leftBorderSum;
}
/*13*/ int maxRightBorderSum = 0, rightBorderSum = 0;
/*14*/ for( int j = center + 1; j <= right; j++ )
{
/*15*/ rightBorderSum += a[ j ];
/*16*/ if( rightBorderSum > maxRightBorderSum )
/*17*/ maxRightBorderSum = rightBorderSum;
}
/*18*/ return max3( maxLeftSum, maxRightSum,
/*19*/ maxLeftBorderSum + maxRightBorderSum );
}
int main(){
double table[ROW_CAP][COL_COUNT];
FILE* inFile;
int nRow;
double maxSum;
int lUY, lUX, rDY, rDX;
inFile=fopen("Table1.txt", "r");
getArray(inFile, table, &nRow);
maxSum=maxSumConstPoint(table, nRow, 2, 3, &rDY, &rDX);
printf("MaxSum Rectangular starting from origin is %.2lf. Its right down coordinate (y,x) is %d, %d\n", maxSum, rDY, rDX);
maxSum=maxSumRec(table, nRow, &lUY, &lUX, &rDY, &rDX);
printf("MaxSum Rectangular is %.2lf. Its left upper coordinate (y,x) is %d, %d, right down coordinate is %d, %d\n", maxSum, lUY, lUX, rDY, rDX);
fclose(inFile);
return 0;
}
/**
* Driver for divide-and-conquer maximum contiguous
* subsequence sum algorithm.
*/
int maxSubSum3( const vector<int> & a )
{
return maxSumRec( a, 0, a.size( ) - 1 );
}
