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来自「浙江大学计算机学院数据结构课程的教学课件」· HTM 代码 · 共 59 行
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<font color="#FF0033" size="5"><b><font face="Arial"> Fast transpose of a sparse matrix
</font></b></font><b><font face="Arial" size="4">
#define MAX-COL 50
void<font color="#FF0033"> fast_transpose</font> ( term a[ ], term b [ ])
<font color="#CC0099" size="3" face="Arial, Helvetica, sans-serif"><i>/* b is set to the transpose of a */</i></font>
{ int row_terms<font size="3">[MAX_COL]</font>, starting_pos<font size="3">[MAX_COL];</font>
int i, j;
num_cols = a[0].col;
num_terms = a[0].value;
b[0].row = num_cols; b[0].col = a[0].row
b[0].value =num_terms;
if (num_terms > 0) { <font color="#CC0099" size="3" face="Arial, Helvetica, sans-serif"><i>/* non zero matrix*/</i></font>
<font face="Arial, Helvetica, sans-serif" color="#FF0000">for</font> ( i = 0; i < num_cols; i++) <i><font face="Arial, Helvetica, sans-serif">row_terms[ i ] = 0;</font></i>
<i><font face="Arial, Helvetica, sans-serif" size="3" color="#FF0099"> <font color="#CC0099"> /*计每行个数*/</font></font></i>
<font face="Arial, Helvetica, sans-serif" color="#FF0000">for</font> ( i = 1; i <=num_terms; i++) <i><font face="Arial, Helvetica, sans-serif"> row_terms[a [ i ].col]++</font></i>;
starting_pos[0] =1;
<font face="Arial, Helvetica, sans-serif" color="#FF0000"> for</font> ( i =1; i < num_cols; i++) <font face="Arial, Helvetica, sans-serif" size="3" color="#CC0099"> <i>/*计每行起始地址*/</i></font><font face="Arial, Helvetica, sans-serif" size="3" color="#FF0099"><i>
</i></font> starting_pos[i] = starting_pos[i-1] + row_terms[i-1];
<font face="Arial, Helvetica, sans-serif" color="#FF0000"> for </font>( i = 1; i <=num_terms; i++) {
j = starting_pos[ a[i].col]++;
b[j].row = a [i].col; b[j].col = a [i ].row;
b[j].value = a[i].value;
}
}
}
<font face="Arial, Helvetica, sans-serif" color="#FF0000">[0] [1] [2] [3] [4] [5]</font>
<i>row_terms</i> = 2 1 2 2 0 1
<i>starting_pos</i>= 1 3 4 6 8 8
<font color="#FF0033">Analysis
</font> <font color="#0033CC">two dimensions</font> O (<i> rows* columns</i>)<font color="#0033CC"> <i><font face="Arial, Helvetica, sans-serif" size="3" color="#CC0099">/*two dimensional*/</font></i>
transpose</font> O (<i>columns * elements</i>)
<font color="#0033CC"> fast_transpose </font> O (<i>column + elements</i>)
<font color="#CC0033"><font face="Arial, Helvetica, sans-serif" color="#FF0000"> worst case elements=rows* columns</font></font>
</font></b></pre>
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