static boolean
isstrong(graph *g, int n)
/* test if tournament g is strongly-connected
* This code is strictly for tournaments only.
*/
{
setword seen,expanded,toexpand,allbits;
int i;
allbits = ALLMASK(n);
seen = bit[0] | g[0];
expanded = bit[0];
while (seen != allbits && (toexpand = (seen & ~expanded))) /* not == */
{
i = FIRSTBITNZ(toexpand);
expanded |= bit[i];
seen |= g[i];
}
if (seen != allbits) return FALSE;
seen = (allbits ^ g[0]);
expanded = bit[0];
while (seen != allbits && (toexpand = (seen & ~expanded))) /* not == */
{
i = FIRSTBITNZ(toexpand);
expanded |= bit[i];
seen |= (g[i] ^ allbits);
}
return seen == allbits;
}
static boolean
distinvar(graph *g, int *invar, int n1, int n2)
/* make distance invariant/
exit immediately FALSE if n-1 not maximal else exit TRUE
Note: only invar[n1..n1+n2-1] set */
{
int w,n;
setword workset,frontier;
setword sofar;
int inv,d,v;
n = n1 + n2;
for (v = n-1; v >= n1; --v)
{
inv = 0;
sofar = frontier = bit[v];
for (d = 1; frontier != 0; ++d)
{
workset = 0;
inv += POPCOUNT(frontier) ^ (0x57 + d);
while (frontier)
{
w = FIRSTBITNZ(frontier);
frontier &= ~bit[w];
workset |= g[w];
}
frontier = workset & ~sofar;
sofar |= frontier;
}
invar[v] = inv;
if (v < n-1 && inv > invar[n-1]) return FALSE;
}
return TRUE;
}
boolean
isbiconnected1(graph *g, int n)
/* Test if g is biconnected; version for m=1. */
{
int sp,v,w;
setword sw;
int numvis;
setword visited;
int num[WORDSIZE],lp[WORDSIZE],stack[WORDSIZE];
if (n <= 2) return FALSE;
visited = bit[0];
stack[0] = 0;
num[0] = 0;
lp[0] = 0;
numvis = 1;
sp = 0;
v = 0;
for (;;)
{
if ((sw = g[v] & ~visited)) /* not "==" */
{
w = v;
v = FIRSTBITNZ(sw); /* visit next child */
stack[++sp] = v;
visited |= bit[v];
lp[v] = num[v] = numvis++;
sw = g[v] & visited & ~bit[w];
while (sw)
{
w = FIRSTBITNZ(sw);
sw &= ~bit[w];
if (num[w] < lp[v]) lp[v] = num[w];
}
}
else
{
w = v; /* back up to parent */
if (sp <= 1) return numvis == n;
v = stack[--sp];
if (lp[w] >= num[v]) return FALSE;
if (lp[w] < lp[v]) lp[v] = lp[w];
}
}
}
boolean
isconnected1(graph *g, int n)
/* test if g is connected (m=1) */
{
setword seen,expanded,toexpand;
int i;
seen = bit[0];
expanded = 0;
while ((toexpand = (seen & ~expanded)) != 0)
{
i = FIRSTBITNZ(toexpand);
expanded |= bit[i];
seen |= g[i];
}
return POPCOUNT(seen) == n;
}
static boolean
isconnected(graph *g, int n)
/* test if g is connected */
{
setword seen,expanded,toexpand,allbits;
int i;
allbits = ALLMASK(n);
expanded = bit[n-1];
seen = expanded | g[n-1];
while (seen != allbits && (toexpand = (seen & ~expanded))) /* not == */
{
i = FIRSTBITNZ(toexpand);
expanded |= bit[i];
seen |= g[i];
}
return seen == allbits;
}
