![\begin{picture}(604,224)(10,605)
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...ox(0,0)[lb]{\raisebox{0pt}[0pt][0pt]{\twlrm DFS Spanning Forest}}}
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main () { void dfs(NODE v) {
NODE v; NODE w;
for (all nodes v) visited[v] = FALSE; visited[v] = TRUE;
for (all nodes v) { for (all neighbors w of v)
if (!visited[v]) if (!visited[w])
dfs(v); dfs(w);
} }
Instead of just TRUE or FALSE: mark each visit with label++
DFS: dfs [170]
% gcc -o dfs dfs.c > tcc dfs.c
Data File with Test Case: graph.dat
Adjacency Matrix (as compared to Adjacency List):
10 1 1 0 1 0 0 0 0 0 0 0 1 1 0 0 1 0 0 0 0 1 0 1 1 1 0 0 0 0 0 0 0 0 1 1 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 1 0 0 1 0 0 0 0 0 0 0 0 0 1 1 1 0 0 0 0 0 0 0 1 0 1 0 1 0 0 0 0 0 0 0 1 1 0 0 0 0 0 0 0 0 0 1 1 % dfs graph.dat n: 10 steps: 100
ANALYSIS: for every node, for every neighbor: O( )
DFS: dfs [171]
DFS Spanning Forest:
% dfs graph.dat graph 0 1 0 0 0 0 0 0 0 0 0 0 1 0 0 1 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 0
DFS: dfs [172]
% dfs graph.dat step # "x" = don't try; "+" = try; "-" = cancel v w step v w step v w step v w step v w step 1 1 1 x 5 8 22 x 6 4 42 x 7 3 63 x 10 5 83 x 1 2 2 + 5 9 23 x 6 5 43 x 7 4 64 x 10 6 84 x 2 1 3 x 5 10 24 x 6 6 44 x 7 5 65 x 10 7 85 x 2 2 4 x 4 6 25 x 6 7 45 x 7 6 66 + 10 8 86 x 2 3 5 + 4 7 26 x 6 8 46 x 7 6 66 - 10 9 87 + 3 1 6 + 4 8 27 x 6 9 47 x 7 7 67 x 9 1 88 x 3 1 6 - 4 9 28 x 6 10 48 x 7 8 68 + 9 2 89 x 3 2 7 x 4 10 29 x 2 7 49 x 8 1 69 x 9 3 90 x 3 3 8 x 3 5 30 + 2 8 50 x 8 2 70 x 9 4 91 x 3 4 9 + 3 5 30 - 2 9 51 x 8 3 71 x 9 5 92 x 4 1 10 x 3 6 31 x 2 10 52 x 8 4 72 x 9 6 93 x 4 2 11 x 3 7 32 x 1 3 53 x 8 5 73 x 9 7 94 x 4 3 12 x 3 8 33 x 1 4 54 + 8 6 74 + 9 8 95 + 4 4 13 x 3 9 34 x 1 4 54 - 8 6 74 - 9 8 95 - 4 5 14 + 3 10 35 x 1 5 55 x 8 7 75 x 9 9 96 x 5 1 15 x 2 4 36 x 1 6 56 x 8 8 76 x 9 10 97 x 5 2 16 x 2 5 37 x 1 7 57 x 8 9 77 x 10 10 98 x 5 3 17 x 2 6 38 + 1 8 58 x 8 10 78 + 7 9 99 x 5 4 18 x 6 1 39 x 1 9 59 x 10 1 79 x 7 10 100 x 5 5 19 x 6 2 40 x 1 10 60 x 10 2 80 x 5 6 20 x 6 3 41 + 7 1 61 x 10 3 81 x 5 7 21 x 6 3 41 - 7 2 62 x 10 4 82 x
DFS: dfs.c [173]
typedef int NODE;
int A[MAX][MAX], B[MAX][MAX];
int n, label, val[MAX];
void DFS(NODE v){
NODE w;
val[v] = ++label;
for (w=1; w<=n; w++){
if (A[v][w] != 0)
if (val[w] == 0) {
B[v][w] = 1;
DFS(w);
}
}
}
main(int argc, char *argv[]) {
NODE v;
getdata(argc,argv);
label=0;
for (v=1; v<=n; v++) val[v]=0;
for (v=1; v<=n; v++)
if (val[v] == 0)
DFS(v);
}