Review the data structure. The cross-linked list is mainly used in two places: sparse matrix storage and directed graph storage.
Sparse Matrix is commonly used for triple storage. However, when the non-zero elements and positions of the matrix change greatly during the operation, they do not adopt sequential structure storage. In this case, cross-linked lists are a good choice.
The following is the data structure of the Cross-linked list, as well as the creation function. There is no post memory release function for a limited space:
Typedef struct qlnode
...{
Int IPOs, JPOs; // row and column subscript of non-zero elements;
Int ielem; // element;
Struct qlnode * right, * down;
} Qlnode;
Typedef struct qlnode * qlink;
Typedef struct
...{
Qlink * rhead, * chead; // header pointer of the row and column;
Int rownum, colnum, totalnum;
} Crosslist;
Bool creatcrosslist (crosslist & crolit)
...{
Int row, coll, total;
Cin> row> Coll> total;
Crolit. rownum = row; crolit. colnum = Coll; crolit. totalnum = total;
Crolit. rhead = new qlink [row]; // create a row header pointer table;
Crorule. chead = new qlink [Coll]; // create a column header index table;
// Initialize the header pointer table;
For (INT I = 0; I <row; I ++)
Crow.rhead [I] = NULL;
For (INT I = 0; I <Coll; I ++)
Crow.chead [I] = NULL;
Int I, j, ELEM; // input in triple format
For (CIN> I> j> ELEM; ELEM! = 0; CIN> I> j> ELEM)
...{
Qlink ptem = new qlnode;
Ptem-> right = ptem-> down = NULL;
Ptem-> IPOs = I; ptem-> JPOs = J; ptem-> ielem = ELEM;
// Insert directly: NULL, or the column coordinate is greater than the maximum column coordinate in the linked list of this row.
// In the same row, the linked list is sorted by column coordinates,
If (crow.rhead [I] = NULL | crow.rhead [I]-> JPOs> J)
...{
Ptem-> right = crow.rhead [I];
Crow.rhead [I] = ptem;
}
Else // query the insert position in the row table:
...{
Qlink BG;
For (BG = crow.rhead [I]; BG-> Right & BG-> right-> JPOs <j; BG = BG-> right );
Ptem-> right = BG-> right; BG-> right = ptem;
} // Insert the row.
// Insert directly: NULL, or the row coordinate is greater than the largest row coordinate in the list.
// In the same column, the linked list is sorted by the row coordinates,
If (crow.chead [J] = NULL | crow.chead [J]-> IPOs> I)
...{
Ptem-> down = crow.chead [J];
Crow.chead [J] = ptem;
}
Else // query the insert position in the list:
...{
Qlink BG;
For (BG = crorule. chead [J]; BG-> down & BG-> down-> IPOs <I; BG = BG-> down );
Ptem-> down = BG-> down; BG-> down = ptem;
} // Insert the column.
}
Return true;
}
// Output elements of each row
Void displayrow (crosslist DEST)
...{
For (INT I = 0; I <DeST. rownum; I ++)
...{
Qlink TEM = DeST. rhead [I];
While (TEM)
...{
Cout <"(" <tem-> IPOs <",";
Cout <tem-> JPOs <",";
Cout <tem-> ielem <")";
TEM = tem-> right;
}
Cout <Endl;
}
}
For example, sparse matrix:
| 3 0 0 5 |
| 0 2 0 0 |
| 2 0 0 0 |
/* Test input:
3 4 4
0 0 3
0 3 5
1 1 2
2 0 2
0 0 0/indicates end */
/* Test output:
(0, 0, 3) (0, 3, 5)
(1, 1, 2)
(2, 0, 2)
Press any key to continue ...*/
The following figure shows the storage of the cross linked list:
