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fix dsu.leader to avoid multiple assert checks #186

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Merged
merged 1 commit into from
May 1, 2025
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fix dsu.leader to avoid multiple assert checks #186

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8 changes: 6 additions & 2 deletions atcoder/dsu.hpp
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Original file line number Diff line number Diff line change
Expand Up @@ -35,8 +35,7 @@ struct dsu {

int leader(int a) {
assert(0 <= a && a < _n);
if (parent_or_size[a] < 0) return a;
return parent_or_size[a] = leader(parent_or_size[a]);
return _leader(a);
}

int size(int a) {
Expand Down Expand Up @@ -69,6 +68,11 @@ struct dsu {
// root node: -1 * component size
// otherwise: parent
std::vector<int> parent_or_size;

int _leader(int a) {
if (parent_or_size[a] < 0) return a;
return parent_or_size[a] = _leader(parent_or_size[a]);
}
};

} // namespace atcoder
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