def main_1(grp):
edge = []
for i in range(len(grp)):
for j, w in grp[i]:
m, n = min(i, j), max(i, j)
if (m, n, w) not in edge:
edge.append((m, n, w))
assert (len(edge) == sum(map(len, grp)) / 2)
edge.sort(key=lambda x: x[2])
ret = []
ds = DisjointSetForest(len(grp))
for i, j, w in edge:
if ds.find(i) != ds.find(j):
ret.append(w)
ds.union(i, j)
assert (len(ret) == len(grp) - 1)
return sum(ret)
def main_Kruskal(self, grp, src=None):
# 1) build array of edges and sort
edge = []
for i in range(len(grp)):
for j, w in grp[i]:
m, n = min(i, j), max(i, j)
if ((m, n), w) not in edge:
edge.append(((m, n), w))
assert (len(edge) == sum(map(len, grp)) / 2)
edge.sort(key=lambda x: x[1])
# 2) build MST by greedily selecting edges
mst = []
ds = DisjointSetForest(len(grp))
for (i, j), w in edge:
if ds.find(i) != ds.find(j):
ds.union(i, j)
mst.append(((i, j), w))
assert (len(mst) == len(grp) - 1)
return mst
def main_1(grp):
edge = []
for i in range(len(grp)):
for j, w in grp[i]:
m, n = min(i, j), max(i, j)
if (m, n, w) not in edge:
edge.append((m, n, w))
assert (len(edge) == sum(map(len, grp)) / 2)
edge.sort(key=lambda x: x[2])
ret = []
ds = DisjointSetForest(len(grp))
for i, j, w in edge:
if ds.find(i) != ds.find(j):
ret.append(w)
ds.union(i, j)
assert (len(ret) == len(grp) - 1)
return sum(ret)
