function for exchanging two rows of a matrix
void swap ( int mat [ R ] [ C ] , int row1 , int row2 , int col ) { for ( int i = 0 ; i < col ; i ++ ) { int temp = mat [ row1 ] [ i ] ; mat [ row1 ] [ i ] = mat [ row2 ] [ i ] ; mat [ row2 ] [ i ] = temp ; } }