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Update graph/virtual_tree.cc 

Signed-off-by: subcrip <contact@subc.rip>
This commit is contained in:
subcrip 2024-09-05 23:50:57 +08:00
parent 47fcbd6011
commit 26b73ce439
1 changed files with 5 additions and 3 deletions
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8
graph/virtual_tree.cc
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@ -24,8 +24,8 @@ struct virtual_tree {
}; };
dfs(dfs, root, 0); dfs(dfs, root, 0);
} }
// returned vertex number starts from 0 // vertex number starts from 0
vector<vector<pil>> generate(vector<int> pivots) { pair<vector<vector<pil>>, vector<int>> generate(vector<int> pivots) {
int m = pivots.size(); int m = pivots.size();
if (m == 0) return {}; if (m == 0) return {};
sort_by_key(pivots.begin(), pivots.end(), expr(dfn[v], int v)); sort_by_key(pivots.begin(), pivots.end(), expr(dfn[v], int v));
@ -40,14 +40,16 @@ struct virtual_tree {
sort_by_key(a.begin(), a.end(), expr(dfn[v], int v)); sort_by_key(a.begin(), a.end(), expr(dfn[v], int v));
m = unique(a.begin(), a.end()) - a.begin(); m = unique(a.begin(), a.end()) - a.begin();
unordered_map<int, int, safe_hash> mp; unordered_map<int, int, safe_hash> mp;
vector<int> rev(m);
for (int i = 0; i < m; ++i) { for (int i = 0; i < m; ++i) {
mp[a[i]] = i; mp[a[i]] = i;
rev[i] = a[i];
} }
vector<vector<pil>> ret(m); vector<vector<pil>> ret(m);
for (int i = 0; i < m - 1; ++i) { for (int i = 0; i < m - 1; ++i) {
int l = lca.query(a[i], a[i + 1]); int l = lca.query(a[i], a[i + 1]);
edgew(ret, mp[l], i + 1, ps[a[i + 1]] - ps[l]); edgew(ret, mp[l], i + 1, ps[a[i + 1]] - ps[l]);
} }
return ret; return { ret, rev };
} }
}; };